still doesn't answer my question 
Probably related to my job...
I'm a "industrial mechanic", it's mostly manual work and also kinda demanding.
Yea but you lift engine block like it's no body's business... yea?
No engine blocks, not that kind of mechanic, more the engineer and metalworker kind of. I build big welded aluminum constructions (lower part of car bodys for high speed trains) which are made of dozens and dozens of pieces. Each piece has to be fitted to measure (grinding) and gets mounted in fixtures for welding (4 small parts welded to one bigger piece + 5 other bigger pieces result in a even bigger piece + some other even bigger pieces resulting in one huge piece, etc...), this involves a lot of crawling and climbing (these fixtures can get huge, train size at the end of the process) and also lots of clamping / pressing / winching / etc. as all the welding causes a lot tension (because of the induced heat and the resulting shrinkage... you would be surprised what kind of bending/deformation heat can cause) so you have to mount stuff over-size or with "negative tension" (forcing stuff in the opposite direction of the shrinkage / resulting tension), sometimes it takes several tons of force to ensure everything ends up straight in the end (tolerances for several meter long pieces are like +/- 4mm, less for the smaller parts as tolerances add up when smaller pieces are put together to a bigger one). Well, the workflow is kinda hard to explain to a "outsider" and I wish I could film it with a go-pro mounted on my helmet (would make a awesome docu), but filming is strongly prohibited (espionage).
But yeah, I also have to carry heavy stuff around or swing a 20 pound sledgehammer
