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.
I ran a drill rig for soil sampling for a few years. One day it was 100F outside and we had to drill inside a drycleaners. They had dryers and steam presses going , so it was a humid 130F inside. We used a remote drill rig which required running 100 lb hydraulic lines from the truck outside. These lines got so hot you couldn’t touch them with a bare hand. So imagine trying to move these heavy as hell lines without them touching bare skin and while having to shift your hands around constantly to avoid burns.
That ties for worst with the day we drilled at a gas station in a farm field in the middle of nowhere where it was -20F not counting the wind chill. The thing about soil sampling for contaminants is you have to wash the drill between holes. At those temperatures everything froze instantly and the machinery kept locking up with ice. It took us 8 hours to do what would normally take 2. And then we got a flat tire driving back…