Clearly our mood is not simply a function of our own personalities. We are also subject to the circumstances in which we find ourselves and the effects of our own choices. What kinds of things truly contribute to sustained happiness and which do not?

The research on what makes us happy is far more complicated than the literature on the benefits of happiness-on what happiness does for us. The earlier happiness researchers were quite pessimistic about the degree of control we have over our own happiness, assuming that we can do little to affect our happiness in any sustainable way. Later researchers had a far more optimistic view, however, suggesting that our activities and circumstances can definitely impact our general level of happiness.