The final insight on happiness I want to give you isn't really an insight on happiness actually. It's more on pleasure, on short-term pleasure, but it's so cool. I just have to talk about it. This is that our judgments about the pleasure and pain of past events are skewed in very interesting ways. This is the work of Danny Kahneman who was a famous psychologist. He won the Nobel Prize in economics for his work, including this sort of work. And here's the experiment I want to run on you, and ask you this question, what would you like better; a medical procedure that's very painful for an hour then it stops? Imagine a dental procedure that's painful or a colonoscopy or anything, anything painful. That's option one. Or option two is the same, exact same medical procedure, very painful for an hour. then the same procedure continues for five more minutes and it's mildly painful. Then it stops. Which would you prefer? A or B? Now this might seem like the stupidest question in the world of course. A is better. The only difference between A and B is that B has more pain in it. So you'd rather have A. It turns out though, and Kahneman did this research in all sorts of ways, including testing people who really were undergoing painful medical procedures, and they find that B leaves a better memory. Well, why? Why would it do that? The answer is that when we look back on past events and assessed their pleasure and pain, we tend to do so not by just summing up the amount of pleasure and pain that they experience, but instead focusing on peeks and endings. You remember the extremes, the biggest moment of pain, the greatest moment of pleasure, and you also remember how it ends. So this leads to an interesting, I think valuable finding, that if you had to distribute pain and pleasure across time, you're much better off putting the pleasure at the end and the pain everywhere else. So imagine a party that's hugely fun at the beginning but it ends badly. At the last minute of party you say something embarrassing, you spill something all over yourself, you get in an argument with a friend. As opposed to an awful party, this is B, that's just boring and unpleasant everything, but it ends just great. You know, a sudden kiss with somebody you've always admired, a very nice compliment, something goes really. Well, you might think if you carefully calibrated the good and the bad, that A, would be much much better, but in the real world that is not quite so. Endings matter so much that a good ending can override a whole lot of bad and a bad ending can destroy a whole lot of good. Endings really do matter.