HVAC - If you build duct, it gets monotonous. If you install it, it can be challenging but beating the other guys to the job site can be difficult. Then everyone is in everyones way. If you service it and your any good, it's not very hard but can be difficult at times with strange problems. BUT, you work on roofs all the time and in any type of weather. There will always be service.
If I could go back and be a CNC machinist or toolmaker, I'd do that in a heart beat. You have to use your head and the things you can do are amazing. It's indoors in a conditioned environment. But, how much manufacturing is there in the US??
If I were a welder I'd want to be a pipefitter welder or underwater welder; The money is unbelievable......
Welding 250 pieces of angle iron to a piece of flat stock would drive me nuts. Thats production welding.
All our government does is distract us while they steal from us, misspend our tax $ and ruin our country