Huh? Tell me that when you're painting the underside of a desk for 5 coats on a concrete shop floor and you don't have the clearance to sit up. Try installing a toilet when you have just enough crawl space next to the water inlet line to fit 3 handspans. Try sitting in the bed of a truck in the summer heat making sure that your ratchets are tied properly. As someone who grew up in a blue collar area, RSI is extremely common. Tennis elbow, worn knees, hip problems, back issues. That kind of hard labor is easy until your mid 20s and then turns more into a liability than exercise. You can always run on a treadmill to lose weight, but no amount of running will repair your knee.