I did drywall for two years both laying sheets as well as finishing work...both were hard on the arms and shoulders but got easy after a while.

I also did CNC saw operations at a custom closet company and regularly carried 100lb sheets of melamine and 140lb sheets of masonite around the shop. Normal night consisted of cutting about 6-8 units of 4'x8' sheets and loading them on carts, a unit consisted of about 40 sheets.

Yeah in both these jobs I was beat for the first month but once I got used to it I was never in better shape.