Actress Jane Fonda, who is 78, may appear to have found the Fountain of Youth. But we think she owes her amazing vitality to a lifelong regimen of exercise and a great attitude.

"We need to revise how we think of aging," says Fonda. "The old paradigm was: You're born, you peak at midlife, and then you decline into decrepitude. Looking at aging as ascending a staircase, you gain well-being, spirit, soul, wisdom ."

A study from Northwestern University agrees: You can make your Real Epigenetic Age a lot younger than your chronological age by making smart choices.

You see, the way genes are turned on and off (that's the field called epigenetics) can be modified for good or ill by your exposure to toxins, chronic stress responses, weight-training; aerobic exercise, diet, and other factors.

The researchers measured 71 DNA methylation markers (molecules that make genes more or less receptive to biochemical signals and determine your epigenetic age) of 442 people from 1999 to 2013.

They then determined that for every year your epigenetic age is older than your chronological age, the risk of getting cancer within three years goes up by 6 percent, and your risk of dying from cancer within five years goes up 17 percent.