Typically, people who exercise start eating better and becoming more productive at work. They smoke less and show more patience with colleagues and family. They use their credit cards less frequently and say they feel less stressed. It's not completely clear why. But for many people, exercise is a keystone habit that triggers widespread change.

The cooperation of NASCAR - or any other system, it turns out - persists only when everyone believes he has the opportunity to win.

Rather, to change a habit, you must keep the old cue, and deliver the old reward, but insert a new routine.

As people strengthened their willpower muscles in one part of their lives—in the gym, or a money management program—that strength spilled over into what they ate or how hard they worked. Once willpower became stronger, it touched everything.

What we know from lab studies is that it's never too late to break a habit. Habits are malleable throughout your entire life. But we also know that the best way to change a habit is to understand its structure - that once you tell people about the cue and the reward and you force them to recognize what those factors are in a behavior, it becomes much, much easier to change.

The brain has this amazing ability to find happiness even when the memories of it are gone.

If you dress a new something in old habits, it’s easier for the public to accept it.