At lunch yesterday I was telling my friend Tom about happiness set point theory, which (backed by substantial evidence) claims that each person has a genetically determined set point for happiness, and when good or bad things happen to them their happiness temporarily deviates from that set point but returns to it very quickly. My friend made a very good analogy between this set point and a person's body weight. There may be a default set point, but with the appropriate lifestyle choices a person can remain permanently on one side or the other of that set point. Although these studies indicate that it's very difficult for people to stay above their happiness set points for very long, this analogy resonated with me because I think it's exactly what I've done. By making the appropriate choices (not about what I put in my body but what I put in my mind) I have been able to make myself substantially happier than I was ten or even five years ago. So I think there's hope even for people with negative set points.