Most people would probably prefer to be happy rather than unhappy. However, alongside great happiness we all see much sadness in the world. What do we understand by happiness in the first place? Notwithstanding depression or other biological factors, can we choose to be happy? Psychological research suggests that we all have a happiness "set-point" that determines our well-being, and that we can learn to be happy. Does free will allow us to choose our level of happiness? Is it a question of attitude, or are some people simply happier by nature than others?