I want to refer you to a terrific NY Times article (http://www.nytimes.com/2009/05/12/opinion/12brooks.html)
that is based on an Atlantic magazine essay (http://www.theatlantic.com/doc/200906/happiness)

It has to do with following 250+ Harvard College men over 70 years to find out who led happy lives and what might have been the sources of that happiness.

Here are two excerpts from the Atlantic Essay that are big determinants:

1. That the only thing that really matters in life are your relationships to other people.”
2. What allows people to work, and love, as they grow old? By the time the Grant Study men had entered retirement, Vaillant, who had then been following them for a quarter century, had identified seven major factors that predict healthy aging, both physically and psychologically.

Employing mature adaptations (see below) was one. The others were education, stable marriage, not smoking, not abusing alcohol, some exercise, and healthy weight. Of the 106 Harvard men who had five or six of these factors in their favor at age 50, half ended up at 80 as what Vaillant called “happy-well” and only 7.5 percent as “sad-sick.” Meanwhile, of the men who had three or fewer of the health factors at age 50, none ended up “happy-well” at 80. Even if they had been in adequate physical shape at 50, the men who had three or fewer protective factors were three times as likely to be dead at 80 as those with four or more factors.

[There are four psychological adaptations that humans make…The healthiest, or “mature,” adaptations include altruism, humor, anticipation (looking ahead and planning for future discomfort), suppression (a conscious decision to postpone attention to an impulse or conflict, to be addressed in good time), and sublimation (finding outlets for feelings, like putting aggression into sport, or lust into courtship).]

…I was talking to my good and ancient (68 1/2 years) friend, Joe, about these four fitness “requirements” for happiness–he doesn’t drink or smoke anymore, but he is definitely overweight and does absolutely no exercise. He does have a college education and a stable relationship, with a girl friend, not yet a wife. So he has a good chance at happiness and well-being, assuming he can start counting today, rather than at age 50, as was done with the Harvard guys.

I urged him yet once again to lose weight and start exercising. There was just one brief period in his life when he walked around a nearby lake and carried Heavy Hands, which are dumbbells that weigh under 15 pounds each.

So in a moment of quiet desperation and ridiculous cooperation, Joe and I came up with a regimen of sexual activity that could be done with Heavy Hands. There would be all kinds of unusual positions, great efforts to keep the cardio exercises going longer and longer. It all seemed quite do-able…as long as the weights didn’t hit him or his partner in the head or any other important parts of the body. I am not going to get into any specifics—that would be for another blog—but use your imaginations and let me know if you like the idea.