Goals rely on willpower and self-discipline. As Charles Duhigg wrote in The Power of Habit: Willpower isn’t just a skill. It’s a muscle, like the muscles in your arms or legs, and it gets tired as it works harder, so there’s less power left over for other things.

Goals rely on willpower and self-discipline. As Charles Duhigg wrote in The Power of Habit:

Willpower isn’t just a skill. It’s a muscle, like the muscles in your arms or legs, and it gets tired as it works harder, so there’s less power left over for other things.