While not body repairable, I have had my ACL replaced so it is fixable.<p>For those non-repairable components what you want to do is build up the muscle around them. People are so scared about hurting their backs that they avoid doing any exercises to make the muscles that stabilize the lower back stronger. I routinely have people tell me at the gym they do not dead lift because they do not want to hurt their backs. The problem is a) learning to DL will teach you how to lift properly and b) it will strengthen the muscles in your back.<p>For the record I tore my ACL doing inverts on the wakeboard. Not exactly typical exercising.