Deep, persistent pain in the shoulder can affect young and old alike. The causes, however,can be very different and require a thorough diagnostic process to understand the underlying problem and lead to a solution. Young, active patients often feel that shoulder pain stems from overuse. This may be the case, but it is important to understand why. Current exercise regimens usually emphasize strengthening the deltoid muscles, but the rotator cuff is largely ignored. This leads to an instability syndrome that can cause pain and even worse, a mechanical deficiency of the shoulder joint. If the pain is a chronic problem, with no history of a single traumatic event, the patient will usually respond to strengthening therapy. This therapy will require diligence from the patient and the therapist.