What is aging? Aging is not a mysterious metaphysical phenomenon. Aging happens in the particulars. Your arteries become clogged. Your arthritis flares up. Age is not just a chronological measurement; it's the rate at which the primary internal guardians of health--your cardiovascular and immune systems--decline. While your chronological age is fixed, your biological age may be years older--or younger--depending on a combination of factors. RealAge...