Relentless

Tim Grover's 2013 book distilling his decades of training Michael Jordan, Kobe Bryant, and Dwyane Wade into a framework for elite competitive performance — centered on the concept of the Cleaner: the person who does what has to be done regardless of how they feel.

Provides the most honest account of what extreme competitive performance actually requires — not inspiration and positive thinking but the elimination of weakness, the inability to turn off, and a total refusal to accept excuses from oneself — making it a counterpoint to the motivational literature genre.