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.

Cravings are what drive habits. And figuring out how to spark a craving makes creating a new habit easier.

Between calculated risk and reckless decision-making lies the dividing line between profit and loss.

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

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

The problem is that your brain can't tell the difference between bad and good habits, and so if you have a bad one, it's always lurking there, waiting for the right cues and rewards.