For the last two years I have taken up running as well as other exercise and urge anyone reading this to do the same it works wonders.One thing that just occurred to me is the absence of a pain I used to get.I’m sure anyone who has ran is familiar with that cramp one gets in the abdomen just off to the side a little.It has been a long time that it’s been gone.What was it? And why does it no longer happen? And why does it happen when one runs? 
It’s a “side stitch”. It’s generally believed to be a cramp or spasm in a muscle or set of muscles in the abdomen, most likely the diaphragm muscle. It’s probably caused by a combination of muscle weakness and excessive bouncing, both of which tend to go away as you run more.
Stretching of the diaphragm ligaments? So says Dr. Tim Noakes, as related by Gabe Mirkin. However, in my experience, they are caused (whatever the mechanical reasons may be) by running too fast, at a speed which you are not accustomed. I used to really push myself in races, running much faster than I ever trained, and I always got them.
I haven’t had them in years, altho I do even less speed work now. (Actually, none, except for races.) Perhaps I don’t push myself like I used to. With age comes wisdom.
Thanks for the response guys and for that cool explaination attached to the link barbitu8.