Today, most people don't just want to live long lives. They want to live long healthy lives, or as the old adage puts it, "to die younger, as old as possible." Most of us want to add life to years, not just years to life.

We all know people who have been very successful at aging - not just the "super elders" who run marathons, but ordinary people who maintain vital, active lives, even in the face of chronic illness.

What are the predictors of healthy aging? The results of a 16-year study of nearly 400 older men and women age 65-95 shed interesting light on some of the key factors.