Yet another study tells us that exercise, even if it starts at the age of 50, is key to “aging successfully.” What does “aging successfully mean?” According to Gretchen Reynolds, who reports on the new study in the New York Times, it “involves minimal debility past the age of 65 or so, with little or no serious chronic disease diagnoses, depression, cognitive decline or physical infirmities that would prevent someone from living independently.” Reynolds reports that researchers at the Physical Activity Research Group at University College London studied records of lifestyle habits and health for 3,454 healthy, disease-free British men and women aged between 55 and 73. Eight years later, the scientists re-sorted the respondents, marking them as having remained active, become active, remained inactive or become inactive as they moved into and through middle-age. The researchers found that people who remained active aged most successfully, meaning they had the fewest major chronic diseases, the least memory loss and less physical disability. And yes, even people who became active in middle-age after having been sedentary in prior years aged almost as successfully, with about a seven-fold reduction in their risk of becoming ill or infirm after eight years compared with those who became or remained sedentary. Read more in the New York Times.