Get some exercise and maintain a healthy weight
We'll combine these two factors for (hopefully) obvious reasons. Now prepare for your brain to hurt. In his book about the Grant Study, titled Triumphs of Experience, Dr. Vaillant challenges one of our most commonly held conceptions: exercise causes good health. He asks instead, "might it not be the other way around?" Among the study samples, exercise at age 60 correlated more highly with health at age 55 than with health at 80 (we'll give you a minute to reread that a few times). Furthermore, health at the ages of 50 and 60 significantly predicted exercise (not health) at age 80.
In other words, health predicted exercise at every age, but exercise didn't predict health in old age. Dr. Vaillant concludes that healthy people exercise, but not necessarily that exercise makes people healthy. Which may seem crazy, but imagine being a 60-year-old with pain in every joint… would you want to go for a jog, or even a walk?
The same goes for cholesterol. While maintaining healthy cholesterol levels early in life may impact vital signs at age 50, the study found that cholesterol at age 50 has absolutely no impact on health and happiness at age 80.
So why did he conclude that exercise and healthy weight are two of the major factors for long life and happiness? Well, that's the beauty of longitudinal studies. While the researchers may not know exactly why "some" exercise and maintaining a healthy weight help people live longer, the research shows that they do! So just make it happen.
Adapt to shitty life circumstances
Life is going to suck (a lot), and your response to said suckiness is what makes or breaks you. Now that study participants are well into their 80s and 90s, researchers have classified responses to pain -- "defense mechanisms" -- into four categories that stretch across a lifetime: psychotic, immature, neurotic, and mature. The ultimate goal is to evolve from psychotic (self-absorbed, power-hungry) to mature (altruistic, healthy emotional outlets) without too many hiccups along the way.
The studies discovered that mature adaptation was by far the most powerful predictor of "successful" aging across a lifetime. Having the defense mechanisms of a 9-year-old at age 60 doesn't bode too well, unless you're running for president, maybe. Poor coping skills generally lead to alcoholism, smoking, depression, unhealthy habits, and all the other usual suspects trying to kill you. Life gives everyone lemons, but it's the people that squeeze the hell out of those lemons that end up happier and healthier into their 80s, 90s, and beyond.