There's a natural instinct embedded in friendship, a sympathy that makes us willing to fight for someone we like when they are treated unjustly.

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.

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

If you want to do something that requires willpower - like going for a run after work - you have to conserve your willpower muscle during the day.

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.

Once you understand that habits can change, you have the freedom and the responsibility to remake them. Once you understand that habits can be rebuilt, the power of habit becomes easier to grasp and the only option left is to get to work.

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.