Suppose you want to live a happy life. Who should you turn to for advice? We normally think that we know best about our own happiness. But recent work in psychology and neuroscience suggests that we are often mistaken about our own natures, and that sometimes scientists know us better than we know ourselves. Does this mean that to live a happy life we should ask scientists for advice rather than relying on our introspection? In what follows, we highlight ways in which the science of happiness could help us live happy lives, but we also argue that, in other ways, our navel gazing will remain indispensable.