I just watched this Utube video on exercise, whether it is good or bad, and how much is good. It was very interesting to me because I learned there are studies that show it to be good for a population in general, but typically in each study there are individuals who may not be helped by exercise or may actually be harmed (eg blood pressure or insulin goes UP with exercise, rather than down, as expected). They are working on genetic tests to determine ahead of time who might respond well to an exercise regimen and who might not. Fascinating stuff.

http://forum.lowcarber.org/showthread.php?t=450453