If you want to change your life, it’s more than telling yourself, “No more excuses.” It’s more than discipline and willpower and having a positive mindset. And it’s more than just believing in yourself when no one else does, when it feels like everything is going against you. Change requires—demands—that you ask yourself, “What are you willing to sacrifice to get where you want to go, to become who you want to become?”

What is hard about change is that you must st...