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.
House removals. 17hr day. 37 degrees celcius. Moved two three bedroom houses.
Used to load shipping containers in the Aussie sun but we’d start early. 32 ton in 25kg bags, 3x week.
Worked as security at a Serbian nightclub. It was not good. Violent, capable coked up Serbs.