Happiness consists in activity. It is a running stream, not a stagnant pool.
– John Mason Good
If the secret to happiness does not lie in increasing our set points or in positively impacting the circumstances of our lives, what is left? Is it possible to attain greater happiness and sustain it? To be sure, most of us do become happier at some point during our lives. Indeed, contrary to popular belief, people actually get happier with age. A twenty-two-year study of about two thousand healthy veterans of World War II and the Korean War revealed that life satisfaction increased over the course of these men’s lives, peaked at age sixty-five, and didn’t start significantly declining until age seventy-five (see p. 64).
This is heartening news. But what precisely can we do to hasten or bolster such increases in happiness? The answer lies in the pie chart theory of happiness. Recall that 50 percent of individual differences in happiness are governed by genes, 10 percent by life circumstances, and the remaining 40 percent by what we do and how we think-that is, our intentional activities and strategies. The secret of course lies in that 40 percent. If we observe genuinely happy people, we shall find that they do not just sit around being contented. They make things happen. They pursue new understandings, seek new achievements, and control their thoughts and feelings. In sum, our intentional, effortful activities have a powerful effect on how happy we are, over and above the effects of our set points and the circumstances in which we find themselves. If an unhappy person wants to experience interest, enthusiasm, contentment, peace, and joy, he or she can make it happen by learning the habits of a happy person.