A movement starts because of the social habits of friendship and the strong ties between close acquaintances. It grows because of the habits of a community, and the weak ties that hold neighborhoods and clans together. And it endures because a movement's leaders give participants new habits that create a fresh sense of identity and a feeling of ownership.

Since the 17th century, insurance agents have been the foremost experts on risk.

But countless studies have shown that a cue and a reward, on their own, aren't enough for a new habit to last. Only when your brain starts expecting the reward--craving the endorphins or sense of accomplishment--will it become automatic to lace up your jogging shoes each morning. The cue, in addition to triggering a routine, must also trigger a craving for the reward to come.

When people have a willpower failure, it's because they haven't anticipated a situation that's going to come along.

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.

Companies aren’t families. They’re battlefields in a civil war.

However, to modify a habit, you must decide to change it. You must consiously accept the hard work of identifying the cues and rewards that drive the habits' routines, and find alternatives. You must know you have control and be self-conscious enough to use it -- and every chapter in this book is devoted to illustrating a different aspect of why that control is real.