I had a leg injury while deployed, and the Naval medic (whatever they are called in the rear areas-I just call them all "medics") had me doing a course of Yoga, to keep the injured area loose. Up to that point, I never once considered trying it out. It certainly worked-I was back walking patrols within 2 weeks. Granted, my other option was manning a radio 12 hours a day, and that may have had SOMETHING to do with it .
Seriously though, try yoga. There are several different types-I was given the military one, which I used then (it was some sort of little booklet), but continued for a while using the Yoga for Regular Guys book (no affiliation, just a happy user). That book breaks down some fundamental exercises, and worked for me when I would need stretching. I need to get back to it, now that I think about it!