I picked this book up as part of the fairly-basic NASM CPT program and I'll have to say, after taking the test, I think it was the most useful bit of information from the whole program. I did all the activities, watched the lectures, the client cueing, took the practice quizzes, tests and midterms. I used several of NASM's official study guides and wore myself out reading it all. Ultimately, I passed my exam, but it wasn't because of anything supplementary. To have a chance of passing the test -- assuming you came into this with little or no similar experience -- you have to get through this book and read about the concepts over and over and over until they make sense. Luckily, the book is filled with helpful bits of advice for how to remember things or just goofball tidbits to help you better understand the concepts. It's a good book, it's going to continue to be a good resource, but I am more thankful than ever that this test is over and I can go back to reading normal stuff again!