Typically, people who exercise start eating better and becoming more productive at work. They smoke less and show more patience with colleagues and family. They use their credit cards less frequently and say they feel less stressed. It's not completely clear why. But for many people, exercise is a keystone habit that triggers widespread change.

The waste from power plants is essentially what is left over when you burn coal. And as we all know, coal is a relatively dirty mineral.

Hiding what you know is sometimes as important as knowing it.

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.

Small wins are a steady application of a small advantage.

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.

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.