You don't get to say it isn't. I wet on a 6 week NHS course for chronic pain, and my mental health due to being in chronic pain. Exercise was one of the foundations of that course, not to make us feel better, or to eliminate the pain, but to make our bodies healthier all round. The stronger our bodies the better or bodies are equipt to deal with chronic pain. Meditation, neurology, and psychology were the other foundations. Exercise was just as important as those 3.