I'm reminded of the old Calvin and Hobbes cartoon in which Calvin asks his dad how they decide what number to put on those "Weight Limit" signs on bridges. His

I'm reminded of the old Calvin and Hobbes cartoon in which Calvin asks his dad how they decide what number to put on those "Weight Limit" signs on bridges. His dad tells him that they drive heavier and heavier trucks across each bridge until it falls down. Then they weigh the last truck and rebuild the bridge. Perhaps you, unlike these imaginary bridge engineers, should settle for a well-informed estimate of the limits of your potential, with a generous margin of safety. It sounds like your health is giving you a lot of hints about where the margin of safety might lie.