It's worth mentioning that there's a difference between working behind a desk, and doing physical labor. I don't know what y'all do for a living, so I'm not directing this comment at anyone in particular. I'm just saying that 80 hours at a computer is nothing like 80 hours of heavy lifting.
That is for sure. I'm not the most in shape person, but I swear I can do more physical labor than I can mental labor in the same period of time. The brain just uses up too much stuff trying to think. Just "doing" something is alot less draining, at least for me.
On being salaried and working long hours, I believe alot of people in the computer industry (software especially) have become jaded for the relatively low return on investment. You bust your ass and pray for 3%. In the end, you will be making less per hour and losing valuable personal time you can never recover.