The human body is meant to move pain free! Nagging muscular injuries are always a result of muscular imbalances. You were not born to have pain in your shoulder, knees, hips, back, or wrist. "Injuries" are an excuse (for the most part).
All these pains can be fixed by strengthening and releasing the appropriate muscles groups in a synchronized way. You want to think of your body as a puzzle and how to unravel tension by working and triggering the appropriate muscular system.
A strong well balanced body will have the ability to move and function pain free in a great range of motion.