I pulled my achilles tendon about 10 years ago and ever since it has been particularly fragile. Angling my foot too far creates an unpleasant sensation and if I

I pulled my achilles tendon about 10 years ago and ever since it has been particularly fragile. Angling my foot too far creates an unpleasant sensation and if I'm not really careful about how I place my foot when running it will put me out of commission for several days. I also had a roommate who injured himself doing squats when he was in his early 20s (20 years ago) and has since had six back surgeries and has to work lying down to manage his back pain. Most people don't seem to realize that even casual exercise, if done improperly, can cause permanent, life-altering injuries.