Chiropractic deals with the function of the nervous system and the structure of the spine. Because the nervous system controls everything in your body, it is vital that it functions without interference.
Massage can relax the muscles and improve circulation, but if the nerves are irritated, the muscles will tighten up again. Chiropractic addresses the cause (irritated nerves) not the resulting muscle tightness/spasm.
Exercise is a vital part of any wellness program, but it is not a substitute for chiropractic care. Wellness means having balance in each aspect of health and chiropractic is the component that allows the others to have the most impact on your well-being.