“The limits of self-control present a paradox: We cannot control everything, and yet the only way to increase our self-control is to stretch our limits. Like a muscle, our willpower follows the rule of“Use it or lose it.” If we try to save our energy by becoming willpower coach potatoes, we will lose the strength we have. But if we try to run a willpower marathon every day, we set ourselves up for total collapse. Our challenge is to train like an intelligent athlete, pushing our limits but also pacing ourselves. And while we can find strength in our motivation when we feel weak, we can also look for ways to help our tired selves make good choices.”