But can be recharged with some downtime. It’s a limited but renewable resource.

Because you have a limited supply, each act will create a win-lose scenario where winning in an immediate situation though willpower makes you more likely to lose later because you have less of it.

-The One Thing, p.65

*I would add a caveat to that. When you do the right thing, the immediate reward can empower you to do the right thing again right away