Once people learned how to believe in something, that skill started spilling over to other parts of their lives, until they started believing they could change. Belief was the ingredient that made a reworked habit loop into a permanent behavior.

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.

Most of the choices we make each day may feel like the products of well-considered decision making, but they’re not. They’re habits.

Shampoo doesn’t have to foam, but we add foaming chemicals because people expect it each time they wash their hair. Same thing with laundry detergent. And toothpaste—now every company adds sodium laureth sulfate to make toothpaste foam more. There’s no cleaning benefit, but people feel better when there’s a bunch of suds around their mouth. Once the customer starts expecting that foam, the habit starts growing.

This is the real power of habit: the insight that your habits are what you choose them to be.

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

There’s something about it that makes other good habits easier.