The Golden Rule of Habit Change: You can't extinguish a bad habit, you can only change it.

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

The biggest moment of flexibility in our shopping habits is when we have a child, because when you think about it, all of your old routines sort of go out the window, and suddenly a marketer can come in and sell you new kinds of things.

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.

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

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.

Habits, scientists say, emerge because the brain is constantly looking for ways to save effort.