THE SECRETS Healthy Aging

How long you live isn't the only thing that matters — how well you live counts too. Experts are aiming their ample brainpower at helping people stay sharp and active for as long as possible. Here are the steps you can take now.

- MERYL DAVIDS LANDAU

Are you hoping to stick around to a ripe old age—say, your late 80s or beyond? If you're like many people, the answer might be no—maybe because you picture being sick or disabled, being a burden to your family or having a poor quality of life.

But what if you could reach a very old age and remain fit enough to manage a 5K or hike steep trails, or at least live independently and keep pace with your great-grandkids?

Scientists today are focused on something new: your health span. Rather than simply helping people celebrate many birthdays, they want to make those older years great ones, says Matt Kaeberlein, Ph.D., CEO of Optispan and a former director of the Healthy Aging and Longevity Research Institute at the University of Washington.

A couple of definitions: Your life span is how many years you're alive. Your health span, though, is how many of those years you are alert, engaged and active, says Stephen Kopecky, M.D., a cardiologist at the Mayo Clinic and the author of Live Younger Longer. With a longer health span, you still may get sick or develop a chronic condition at some point, but if you do, it won't put too big a crimp on your later years.

What Makes Us Feel Elderly?

Conditions we associate with aging typically start in our cells and tissues before they become visible, and health span scientists are trying to figure out what causes these to get so messed up as we get older. The list so far includes dysfunctions of mitochondria, the engines of cells; shortening of telomeres, substances at the ends of chromosomes that act like shoelace tips to keep them from fraying; and glitches in info transfer between parts of a cell.