Then one day, we’ll put the reward in the old place, and put in the rat, and, by golloy, the old habit will rememerge right away. habits never really disappear. They’re encoded into the sturctures of our brain, and that’s a huge advantage for us, because it would be awful if we had to relearn how to drive after every vacation. 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.

Companies aren’t families. They’re battlefields in a civil war. Yet despite this capacity for internecine warfare, most companies roll along relatively peacefully, year after year, because they have routines—habits—that create truces that allow everyone to set aside their rivalries long enough to get a day’s work done.

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.

America is the Saudi Arabia of coal.

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.

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.

There’s something really powerful about groups and shared experiences. People might be skeptical about their ability to change if they’re by themselves, but a group will convince them to suspend disbelief. A community creates belief.