joint damage

In the absence of information about what the optimal amount of exercise for general well-being is with regards to joints or anything else, I fail to see what more could be done than to take the ordinary precautions. If you know what the signs are that you're damaging your joints or any other part of your body, and you're vigilent in looking out for those signs, the benefits seem to me worth the risk, especially since abstaining from exercise has its own associated risks, e.g. heart-disease.

I think a lot of people override the relatively subtle information that they're hurting themselves

Well, why? If these signals are subtle then how can we know when we might be overriding them?