Jump to ratings and reviews
Rate this book

The Glass Box: The Shocking True Story of How CrossFit Broke the Rules, Made Millions, and Changed Fitness Forever

Rate this book
An eye-opening and wildly entertaining book about the multimillion-dollar fitness phenomenon CrossFit and its mercurial founder, Greg Glassman—from an investigative journalist and regular contributor to the New York Times.

How did an upstart workout regimen, begun out of commercial gyms in Santa Cruz in the ‘90s, become one of the most popular and polarizing fitness platforms in the world? And who, exactly, is the person responsible for its success?

The Glass Box is a page-turning and upsetting look at CrossFit—one of the most popular fitness programs in the world—and at its divisive founder, Greg Glassman. Written by veteran journalist Calum Marsh, it is both a thorough history of a company’s rise and an eagle-eyed examination of what happens when a visionary idea marches headlong toward global expansion.

CrossFit is a phenomenon, and its studios and methods are now ubiquitous. But the company’s culture of unapologetic machismo, and the sometimes reckless behavior of Glassman and his cronies, repeatedly put the brand, and its founder, in the hot seat—until one careless mistake too many brought the empire crashing down.

347 pages, Kindle Edition

Published October 27, 2026

Loading...
Loading...

About the author

Calum Marsh

2 books44 followers

Ratings & Reviews

What do you think?
Rate this book

Friends & Following

Create a free account to discover what your friends think of this book!

Community Reviews

5 stars
19 (29%)
4 stars
26 (40%)
3 stars
16 (25%)
2 stars
2 (3%)
1 star
1 (1%)
Displaying 1 - 18 of 18 reviews
Profile Image for Olivia.
674 reviews5 followers
Review of advance copy received from NetGalley
June 4, 2026
Received an advanced reader copy from NetGally.

I love a good long long form (book!) investigative piece. This one though, I could not tell if the author was buying the Glassman as a charmer, despite the evidence OR if he absolutely disdains the man, but included lines that felt absolutely false because we have to beleive that somehow--this man convinced a following of folks to join his cult. I struggle with this because he repeatedly told us how everyone loves him and how great he is...while simultaneously ONLY telling us about how shitty this man was and is and what an absolute entitled asshole he is to everyone he meets.

Overall, the book read pretty quick-- which is thanks to the author crafting a propelling story. But I did want more of a definitive voice from him-- as he was SAYING one thing, but was conveying and evidencing another. Also, some bits at the end I thought demanded more digging.

But to the subject of the book-- let me vent-- the loser that founded CrossFit, Greg Glassman. First, in his early life, we get a glimpse of red flags when he was MAD that the UCLA women's gymnastics team got the attention and more funding. You know, like men's sports teams do in every other college and university--even when the women's teams out preform them.... MK bro. Fucking be mad about it. Oh, and more sexism from his early life-- he didnt like literature class because women talk. Seriously, he is quoted DIRECTLY: some little girl [..] would put up her hand and talk through the whole thing. I don't know-- maybe if you were smart enough to understand it, you too could have put up your hand and discussed it. There is plenty of evidence in this book that he has zero problems bloviating to anyone who has the displeasure of being in his space. So, right off the bat, we know he's a sexist prick.

The man also has... NO? concept of a dollar. the absolute shitshow of all the expenses racked up-- from the ONE OF A KIND dumbbell that he absolutely required when he was barely off the ground (that costed a fortune) to the eventual private jet he would use for him and his equally sad Yes Men to go to some concert or another and then randomly demand the plane land so they can hit up a drive through before their final destination.

There's about a billion instances of him being an asshole-- yelling, screaming at people-- only to think it's no big deal as he pretends like that's normal behavior; sending literal bullies after people that disagree with them (these men would eventually build a slew of fake profiles to harass people online); and let's not forget the sexual AND physical assault allegations by an ex-girlfriend-- WHICH this author did not do enough to dissect. Instead, he interviews a woman who fucking quit her job as a journalist because she was upset at these allegations against Glassman and decided this woman she never met was lying on the basis that other women who knew him didnt know for sure if it was true. OMG, i wanted to scream.

This man deserves nothing but misfortune.

I always felt judgy about CrossFit, tried it a few times... it was fun. I enjoyed it... was it that some there--def not all!--but for sure some that would accept and even admire this type of despicable behavior,... so, not for me. And, is. it now that I am realizing this all tracks, because THIS type of man, who somehow lucks into surrounding himself by people that are much more capable than he-- was the man behind it all?

Thanks to NetGalley and HarperOne for the ARC.
Profile Image for Katie.
40 reviews
October 28, 2026
Calum Marsh tells the story of Greg Glassman and the rise of CrossFit. No doubt, CrossFit has been highly influential over the last 15–20 years, changing how everyday folks and elite athletes train. Those involved in or familiar with functional fitness will likely find this an entertaining read. Others interested in corporate leadership might enjoy it, too, if only to take notes on how not to run a company.

For others like myself, who are knee-deep in the functional fitness space, the book may leave us disappointed and equally baffled.

CrossFit the company has found itself in a precarious position. With the explosive popularity of HYROX and the emergence of other competitors, I wanted to hear more of Marsh’s take on how CrossFit plans to stay relevant. Or, perhaps more importantly, whether it is even possible at this point.

Glassman’s incompetence, enabled in part by the yes-men surrounding him, including Dave Castro and others, has created a company culture with zero vision, zero planning efficacy, and a caveman-like ability to adapt to an ever-evolving fitness and wellness landscape.

Which is ironic, given CrossFit’s claim to prepare its athletes for the “unknown and unknowable.” Wouldn’t a man so infatuated with the free-market system anticipate that competitors would eventually emerge? HYROX, ATHX, WFP, and others are hardly surprising developments. Competition is the very thing Glassman supposedly champions. Yet CrossFit seems to have been caught flat footed by the changing landscape around it.

The contradictions within the CrossFit community are perhaps most apparent in Glassman himself. He preaches limiting carbohydrates, avoiding alcohol, and addressing the root causes of metabolic disease. Yet his reported drinking habits and drug use stand in stark contrast to the lifestyle he advocated. Why, then, does he continue to have such a cult-like following? Why do so many in the online community still regard him as something of a messiah?

CrossFit has undoubtedly helped many people become fitter, stronger, and healthier. But it is obviously not the cure. No single training methodology is. For all of Glassman’s claims about CrossFit as a solution to the metabolic disease epidemic, the contradictions between the message and the messenger seem to have done little to shake the faith of his most devoted followers.

In much the same way that Glassman wanted CrossFit to be different from the mainstream, he eventually became the mainstream. And just like the fitness trends he once positioned himself against, CrossFit has often fallen back on the same tired response when people fail to see the promised results: blame the individual. If the program doesn’t work, you weren’t committed enough. You didn’t follow the prescription. You didn’t put in the work.

In true American fashion, the solution is to blame individuals rather than examine the broader circumstances shaping their health. Never mind the limitations of the methodology, the price of a gym membership, or the complexity of human health. When the purported cure fails, the individual is the problem.

In this way, CrossFit has become just like every other fitness trend it claims to be so different from.

These contradictions extend beyond Glassman. The community can be remarkably insular, elitist, and resistant to outside criticism. Nutrition advice is often driven more by personal anecdotes and ideological allegiance than scientific evidence. After all, according to Glassman, “science is broken.” Don’t worry, he’s created another company to address that.

This defensiveness has seeped into the media ecosystem surrounding CrossFit, where personalities and outlets such as Sevan Matossian, Andrew Hiller, and The Barbell Spin have become entangled in the divisions over Glassman, the company, and its critics. The conversation often seems less interested in constructive debate than in choosing sides. It becomes less about what CrossFit could do better and more about who is for or against it.

There are deeper cultural questions here, too. CrossFit’s militaristic and evangelical influences have helped shape a community in which training becomes more than exercise. For some, it is an identity, a moral framework, even a kind of religion. When a fitness methodology becomes inseparable from someone’s identity, questioning the methodology can feel like questioning the person.

I do wonder whether Marsh himself is occasionally too restrained in exploring these contradictions. Perhaps there is a reluctance to offend a community accustomed to seeing itself as perpetually under attack. To be fair, the book lays the groundwork for the history and rise of CrossFit, not necessarily its downfall. Marsh cannot cover everything. Still, given the company’s current position, I found myself wanting more.
With HYROX’s success, the emergence of other competitors, the proliferation of individual programming, and the growth of home and garage gyms, how does a community like CrossFit survive? What is its value proposition today? Is it the methodology, the brand, the affiliate model, the competition, or the community itself? And if the community is the answer, what happens when it becomes so resistant to change that it alienates the very people it needs to retain?

These are the questions I was hoping Marsh would explore more deeply. CrossFit’s organizational shortcomings suggest a company at risk of continuing to lose ground. It is not enough to build something influential. You have to be able to evolve it.
People have left CrossFit, and many will never go back. Not necessarily because they stopped caring about fitness, but because they found other ways to train, other communities to join, or simply grew tired of the culture surrounding it.

For those craving a deeper examination of CrossFit’s militaristic, evangelical, and quasi-religious themes, The Cult of CrossFit is an excellent companion read.

Ultimately, The Glass Box is an entertaining and worthwhile account of Greg Glassman and the rise of a fitness phenomenon. For those of us already immersed in the functional fitness world, however, it raises as many questions as it answers. I came away wanting less of a history lesson and more of an examination of what went wrong, why the contradictions persist, and whether CrossFit can find a way forward.

CrossFit changed the fitness industry. That much is undeniable. Whether it can change itself may be the more important question.

Profile Image for Janine.
2,865 reviews39 followers
Review of advance copy received from NetGalley
September 18, 2026
Interesting examination of the rise and fall of CrossFit, an exercise program not easily defined - in fact, the author gives three definitions in the Epilogue.

I knew nothing about CrossFit except its name when I requested this ARC (my thanks to NetGalley and HarperOne for granting me access). What I soon learned was that CrossFit’s influence remade “every gym in its image: Step into every gym in the world today and you will see kettkebells, medicine balls, rowing machines . . . .” It’s also kind of dangerous particularly the death in 2024 at the CrossFit Challenge. The chapter that calls this out notes too that CrossFit seemed to have a totally uncaring attitude about the athletes who participated in the event - unlike other athletic challenges.

The book is a chronological story of CrossFit’s founding by Greg Glassman, its phenomenal rise in California, and with the addition of influencers’ ideas seem to start an internal disintegration of Glassman’s vision. What was pretty hard to read was what Glassman was willing to do in his exercise regime - kind of seemed to me to go beyond the pale.

This was an engrossing read for me. Readers who enjoy nonfiction books about business and the demands of vision and leadership should enjoy this one. But readers like me - trivia buffs of sorts - should find it interesting as well.
Profile Image for Lydia Wagner.
235 reviews2 followers
July 21, 2026
The Glass Box would have been better with more personal anecdotes but read as dry and mostly corporate throughout. An interesting story that deserved a more human telling.
19 reviews1 follower
November 1, 2026
The person they chose to read this audiobook did absolutely zero homework on how to pronounce the names of the people included in the book.
877 reviews6 followers
Review of advance copy received from NetGalley
June 13, 2026
Full Disclosure: I received an Advanced Reader's Copy of The Glass Box: The Shocking True Story of How CrossFit Broke the Rules, Made Millions, and Changed Fitness Forever by Calum Marsh from HarperOne via NetGalley. This book will be published around October 27, 2026.

I'll admit I had some preconceived notions about the cult of CrossFit prior to reading The Glass Box: The Shocking True Story of How CrossFit Broke the Rules, Made Millions, and Changed Fitness Forever by Calum Marsh. The first notion was that it is culty as the CrossFit adherents are pretty adamant that their way is the best way. It looked tough. It didn't always look safe. This book didn't necessarily convince me I was wrong, but it did give me a much better appreciation of why people get so into CrossFit and how the diet and exercise CrossFit promotes does have science behind it and does produce results even if the execution is sometimes flawed. I now realize how many of our current fitness trends have their roots in CrossFit. If you are/were ever into CrossFit or CrossFit-curious or enjoy reading about fitness, you will want to read this book.
Profile Image for Lisa.
222 reviews8 followers
Review of advance copy received from NetGalley
May 31, 2026
I knew very little about CrossFit before reading this book, only that the workouts sound really hard and not something I would like to put myself through. I picked this up because I enjoy reading books about the paths that successful businesses have taken - where the idea came from, what the early days were like, how they knew they were on to something, and how they scaled. The Glass Box covers all that, with a focus on the founder Greg Glassman, who seems like quite a character. I can't say that I found the story particularly shocking, but it was definitely interesting to read about how he got the idea for CrossFit and turned it into a phenomenon. There are a lot of people in this book. I had a hard time keeping track of them all and their relevance to the story.

Overall this would be an interesting read for someone who's into CrossFit or likes reading about how businesses start up and develop. Thanks to NetGalley and HarperOne for the ARC. All opinions are my own.
Profile Image for Ariana.
6 reviews
Review of advance copy received from Author
August 4, 2026
I can’t believe how much I found myself compelled to keep reading about a topic I knew nothing about before starting this.

Corporate Gossip (complimentary) as a genre is something I’ve recently learned that I love. It feels like I have no business hearing all of these behind-the-scenes details. There’s something especially fascinating to me seeing how drama among men with fragile egos plays out, and this book had no shortage of drama.

The way Glassman spends money on his family, friends, colleagues and this dream is probably exactly how I would with unfettered access to millions. He comes off as someone who really loves to have fun while also being the sort of person I would certainly hate to be around regularly, work for, or god help me, be married to.

Thank you to my friend Cal for the advance copy and congratulations on your first book.
1 review
Review of advance copy received from NetGalley
August 13, 2026
Incredible investigative research and captivating storytelling about a founder who, against all odds, it seems at times, manages to create an empire that almost destroys itself through lies, power plays, and manipulation.
Combines an anti-hero thriller-esque novel, meets business case studies, and an in-depth research account of the CrossFit industry from inception to now. Truly mind-blowing. A book written with such lucidity and articulation, uncovering Greg Glassman and CrossFit has never been published before.

The best non-fiction mystery thriller I’ve ever had the pleasure of reading.
Profile Image for Alex Adkins.
221 reviews3 followers
November 8, 2026
The Glass Box effectively details the meteoric rise and even faster fall of Crossfit. Granted the author is a journalist, it does read like a NYT article, heavily worded with romantic language when cutting to the chase would be more impactful. I think the lack of stalwarts within the Crossfit community featured in the book and including their thoughts detracts from the message. Likewise, I think the book speeds through on how much of a toxic culture Glassman created
Profile Image for Sarah.
57 reviews
November 8, 2026
Glassman is a pompous unapologetic asshole that got lucky surrounding himself with people who bailed him out time and time again. He thought he was smarter and better than everyone and trademarked a fitness program that became a wild success. As a long time (and still active) crossfitter, that's all you need to know. I think this would turn more people anti crossfit knowing the jerk that created it rather than give the real community of positivity and fitness a shot. Bummer.
Profile Image for Michael.
5 reviews
October 28, 2026
Great Read!

Enjoyed this expose and well researched narrative about the birth of CrossFit and its demise as an organization, not its methodology. I felt very different about Glassman halfway through the book, but now that I’m finished I understand the controversy of his character much better.
Profile Image for Becca.
441 reviews31 followers
Review of advance copy received from NetGalley
May 13, 2026
Journalist-written exposes are one of my favorite kinds of nonfiction, typically because they're written like longform articles, which I love. This one? Not so much. The writing didn't pull me in, and the "shock" promised in the title didn't seem to emerge with any speed.
Profile Image for Jessica Johnson.
155 reviews3 followers
October 28, 2026
I exercise regularly, but have never done CrossFit, I still found this to be an interesting story. I hadn’t realized the founder was such a character. This story peeked behind the curtain of a well-known brand.
Profile Image for Jared Blum.
130 reviews1 follower
November 2, 2026
Having started CrossFit after the departure of Glassman, I didn’t understand how important he was to the movement. Reading this book also helped me better understand the relationship of the Games to the bigger system. I’m not sure that anyone who hasn’t done CrossFit would be interested though.
17 reviews
November 9, 2026
Very interesting read. Having been in the CrossFit community for over 18 years, I know some level the goings on but to hear of Glassman antics put in such a matter of fact way was eye opening. I would have loved more front the Santa Cruz days but alas.

Good read for those in or around CrossFit or just want a look behind the curtain.
Profile Image for Jessica Corrigan.
111 reviews
June 1, 2026
Thank you NetGalley for the uncorrected e-copy. The backstory of Cross Fit interested me. It started out steady but ultimately I couldn’t finish this about 70% in, and at about 50% in I was dragging through this long-winded and overly verbose recount of Glassman’s beginnings of CrossFit to its exploding into mainstream fitness. Unfortunately it needs like a magazine article that goes on for hours with too many unnecessary direct quotes.
Profile Image for Ron S.
429 reviews33 followers
Review of advance copy received from Publisher
May 21, 2026
A look at CrossFit and founder Greg Glassman that is both revelatory and hugely entertaining to read. A must for CrossFit devotees and those interested in physical culture and functional fitness. Big thanks to HarperCollins Canada library sales rep Ros Steel for the advance copy.
Displaying 1 - 18 of 18 reviews