I didn't used to think it helped, but I recently have noticed that when I begin my day with vigorous exercise, my day's moods are much better than on days that I did not start at the gym.

For your situation I would strongly suggest consulting either or both a physical therapist or physical trainer who specializes with injuries (If you can find a physical therapist who is also a certified trainer, that would be awesome. I would see both, if it were I.) Those types would be most helpful in developing an exercise plan that works for your body's specific issues.