``Fat people ride bikes and go for walks, healthy people run/jog.``...
Yep, just ask Jim Fixx...
http://www.halhigdon.com/Articles/Fixx.htm
BTW, as you get older, factor knees ands hip joints into your equation. Life has a real bad habit of creeping up on you...and genetics can go against you, even when you`ve had years of cardiovascular conditioning...testify!
Ah, youth (did someone say it`s wasted on the young?)!
Regards