The "trades" covers a lot of ground. Some of it is going to be hard on your body. But electrical is probably less bad in general. I also have a friend who is (or at least was) in the steelworker's union; she got into HVAC after Ringling Brothers clown college didn't land a permanent gig. She mostly does design work. Not everything is roofing, which as a peer wrote is probably fairly tough in general.