When we have bad joints, we need to strengthen all of the muscles that cross that joint. For example, with your knees bothering you, you want to make sure that are training your quads, hamstrings and calves in a balanced fashion. The more muscle we have surrounding the joint, the more support the joint has. I have found that resistance training has done wonders for me with any injuries that had occurred in my competitive gymnastics days. One more thing, are you taking any joint support formula?