Exercise is wonderful for people with CCD, but should be tailored to each individual. I don't have collar bones, so I don't have very much upper body strength. I just don't lift a lot of weight, or I could hurt myself. Cardio and many different types of sports can be very effective exercise for people with CCD. Tennis was very fun for me, because you don't need to be very tall to do it, and you don't need massive amounts of strength either.