There are so many interesting parts, its hard to nail down one quote. Two that stick out:
This means that a glimpse of any one moment in a life can be deeply misleading. A man at 20 who appears the model of altruism may turn out to be a kind of emotional prodigy—or he may be ducking the kind of engagement with reality that his peers are both moving toward and defending against. And, on the other extreme, a man at 20 who appears impossibly wounded may turn out to be gestating toward maturity.
and
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 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.
What factors don’t matter? Vaillant identified some surprises. Cholesterol levels at age 50 have nothing to do with health in old age. While social ease correlates highly with good psychosocial adjustment in college and early adulthood, its significance diminishes over time. The predictive importance of childhood temperament also diminishes over time: shy, anxious kids tend to do poorly in young adulthood, but by age 70, are just as likely as the outgoing kids to be “happy-well.” Vaillant sums up: “If you follow lives long enough, the risk factors for healthy life adjustment change. There is an age to watch your cholesterol and an age to ignore it.”
Here's a few songs about being (un)happy.
33forever Being or not being happy