The Marshmallow Test: Mastering Self-Control
by Walter Mischel, 2014

The marshmallow test was an experiment that checked whether kids would hold out eating a visible treat in order to get two of the treat after a wait. Turns out that this self-control was highly predictive of success in life. This book is by the architect of the original experiment and discusses ways to increase self-control to improve outcomes in life. Pairs well with Willpower.

The audiobook version is read by Alan Alda! Which makes everything better.