Don't despair, we're not all like that, I experience this from the opposite viewpoint, patients often ask if I've done anything over the weekend and when I say "Oh, I did a fell run", or "I did the Haworth Hobble" and I tell them how far it was etc I get the usual "You should know better", "Your knees will be shot when you're older" etc etc.
I've given up trying to correct their misconceptions now and just utter a mild chuckle for their benefit.
When I get a fellow runner in it brightens up my day no end and we usually end up having a long chat re races, training etc.