[somenameforme]

The problems aren't in the regular physical work. Our bodies were made to work and get stronger and more resilient with exertion. An average tradesman without some secondary issue like alcoholism is going to be in far better shape than your average programmer. The issue is that in the trades, and any physical work, there's always a chance of some freak accident. Fortunately these are extremely rare, and getting ever rarer over time, but they do exist. By contrast in software the worst somebody's going to have is falling out of their chair or slipping on the floor.