The Forty Percent Is it possible to become happier? Believe it or not, the answer is yes--and the great news is that we have forty percent control over our happiness. If we think of our lives as a pie chart in which our circumstances represent ten percent, and our set point--our genetically determined predisposition for happiness or unhappiness--represents fifty percent, that leaves us with forty percent of intentional activity. What makes up that forty percent? Our behavior does. Besides our genes and the situations we encounter, the way we choose to think and behave is the one critical thing left. We can see that the key to happiness lies in our daily intentional activities--not in changing our genetic makeup or life circumstances. All of us could be happier if we scrutinize what precise behaviors and thoughts happy people naturally and habitually engage in.