I’ll intellectually/emotionally/physically hard as answers. For me its either 12 hours straight “punching tubes” on a very large scotch marine firetube boiler at the beginning of my career or Easter around a decade ago when I was working with troubled teens and had to engage in 5 separate protective holds in one 16 hour double shift. The former was all physical and the latter was a combination of emotional and physical.
Yeah that was 11 years ago and I did the field service portion of that job for like a year, I was fresh out of trade school and working as a grunt for GE as a 22 year old. Until GE decided they were gonna move the business to Germany and Japan and shut down the whole factory.
It had its perks, I got a $75 per meal allowance and could put beer on it and shit. I let someone take over my room for the year back home and had basically no living expenses, just stayed in nice hotels in vegas and some rink-a-dink ones in the middle of the desert. It let me pay off all my loans in a year (which were only like $10k from a 9 month trade school thing)
Anyway I stuck with doin heavy industry electrical work for a while. Now I have a much cushier job doing testing, QA, a bit of design work when applicable, and field service for some absolutely massive electrical systems for steel mills. These things push 6-10k amps thru busbar systems we fabricate from scratch, and are all custom. I do work a lot of OT still but I have a way better work / life balance now