psheehan,
While it is entirely possible you are right that tendonitis is a sign you need to slow things down, Pete Egoscue, author of
Pain Free believes most pain syndromes are a result of biomechanical dysfunction, not overuse. Whether this is true or not, I do not have near the knowledge to determine, however, Egoscue does make a compelling case. I think most people with pain type problems that have tried traditional physical therapy exercises should at the very least give his program of exercises a try. There is so much to potentially gain. I am not affiliated with him in any way.
http://www.peteegoscue.com
Matt