"The word for happiness is cognated with luck. So 'happ' is the root of happiness, happenstance, perhaps, what happens to you. Happiness is something dispensed by the gods, so call no man happy until he's dead because life may look good now, but a piano might fall on your head tomorrow," McMahon says.
Enter the Greeks: Socrates, Plato and Aristotle. They began suggesting that maybe, you have a role in your own happiness.
Aristotle, McMahon explains, "says that happiness is a life lived according to virtue, an active endeavor that one carries on over a lifetime.
The early Christians on the other hand figured that life on earth was all about suffering and sin. Happiness came in the hereafter. But by the 18th century when Jefferson wrote the Declaration of Independence, the pursuit happiness in the here and now was a notion whose time had come.
"The pursuit of happiness enshrines the sense that we can make the world. That we can shape it as we would like, that we can do wonderful
things in this world and that's so much a part of the American experiment in a wonderful way," McMahon says.
And it seems to be working: in a recent poll by the pew research center, 84 percent of Americans describe themselves as pretty happy or very happy.
But then why are there shelves of happiness how-to books published every year? What does makes people happy?
Dreaming of winning the lottery? Psychologists say money does buy happiness, but only if you're poor to begin with. Once you're secure, more money doesn't make much difference.
What is it about American culture, that our expectations are constantly being ratcheted up?
"What we find is a heavy burden on some people thinking they should be happier than they already are," says University of Illinois psychology professor Ed Diener.
"Say somebody who is a 7 on a 10-point scale of happiness who thinks, 'Oh, I've got to be an 8 or a 9' and what I wanna say is, 'Maybe, but maybe, a 7 in fine.'"
Diener researches the components of happiness. Compared to other countries, the United States ranks 15th behind Puerto Rico, Iceland and Canada.
"Life satisfaction hasn't gone up in the U.S. So in 1946, the first national life satisfaction data were collected and we looked at life satisfaction since then and it's like this: flat," Diener explains.
Diener is actively campaigning for wellbeing to be reported the way the unemployment rate is or the Dow Jones Industrial Average.
Diener says if Americans' wellbeing were measured, "we would pay more attention to it and in particular, policymakers would pay more attention to it."
In other words, a kind of pursuit of happiness index. In 40-something years of research, Diener has learned that there is a lot more to happiness than smiles and fun.
"The happiest people, every single one of them has supportive family and friends. There are no exceptions. What leads to long-term happiness is pursuing that next goal, going after the things we value and enjoying the activities that it takes to get there rather than having the goal itself. So the pursuit of happiness might actually be long-term happiness," he says.
It could be taking out the garbage, caring for horses or fill in the blank. Maybe happiness is a journey, not a destination.