Ughh...iPad ate my awesome post about the epiphany I had about exercise and epigenetics. I don't feel like re-writing right now, however here is the short version.
You get handed a set of genes ( thank you mom and dad) BUT how those genes are turned on and off are affected by what we do, eat, are exposed to, etc. So, exercise actually codifies how your genes express themselves. You can't change your genes, but you can change which ones are active. I didn't learn a out this in intro to genetics at York U back in 93!
I like this one: Reported information about the impact of a behavior (exercise), inherently involved in the daily human routine, on the epigenome opens exciting new directions and therapeutic opportunities in the war against neurological and psychiatric disorders.
More here for technical geeks: