By far the biggest predictor of whether something gets done is whether it’s fun to do.
The problem with the genre of “life lessons from the world’s most successful entrepreneurs” is one of causal direction: just because Elon Musk works 120 hours a week, it doesn’t follow that if you work 120 hours a week, you’ll experience Musk’s success. (Whether or not Musk has an enviable life isn’t the point here; that depends on your enthusiasm for space travel and defaming cave divers.) Musk works insane hours because he wants to. We can argue about the psychological roots of that wanting: does it stem from a big-hearted desire to help humanity, or a pathological workaholism and desperation to prove himself? But either way, in some sense, Musk likes it; whereas if you tried to follow that schedule, you’d have to make yourself do it. The same applies to less extreme advice. “Write every day” won’t work unless you want to write. And no exercise regime will last long if you don’t at least slightly enjoy what you’re doing.