Impact is rewarding. Mattering makes us happy.

People are happiest when they're trying to achieve goals that are difficult but not out of reach.

Few of us can accurately gauge how we will feel tomorrow or next week. That's why when you go to the supermarket on an empty stomach, you'll buy too much, and if you shop after a big meal, you'll buy too little.

We are happy when we have family, we are happy when we have friends and almost all the other things we think make us happy are actually just ways of getting more family and friends.

When we have an experience -- hearing a particular sonata, making love with a particular person, watching the sun set from a particular window of a particular room -- on successive occasions, we quickly begin to adapt to it, and the experience yields less pleasure each time. Psychologists call this habituation, economists call it declining marginal utility, and the rest of us call it marriage

The eye and brain are conspirators, and, like most conspiracies, theirs is negotiated behind closed doors, in the back room, outside of our awareness.

The good news is that going blind is not going to make you as unhappy as you think it will. The bad news is that winning the lottery will not make you as happy as you expect.