8 Best Books on  Self-Discipline and Willpower.

No Excuses: The Power of Self-Discipline by Brian Tracy.

The Power of Habit by Charles Duhigg.

Willpower: Rediscovering the Greatest Human Strength by Roy F. Baumeister, John Tierney.

Essential Zen Habits: Mastering the Art of Change by Leo Babauta.

The Practicing Mind by Thomas M. Sterner.

Atomic Habits by James Clear.

The Willpower Instinct by Kelly McGonigal.

The Compound Effect by Darren Hardy.