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.

Did you stop to think before typing this comment or do you just fade in and out?

There's no requirement to sit at a desk, you can use a standing desk or in my case I actually use a treadmill at varying heights inclines and speeds while typing in a computer using an economic keyboard.

I did some landscaping work during summers while in university and it can be absolute hell on your joints - now stack that 40 hours a week for years.

Yeah... have fun with that.

Definitely not wearing out their back and knees