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.
Working as a laborer putting in asphalt driveways in 100-degree summer heat. It’s backbreaking work even without the heat.
The upside was that I grew shoulders and back muscles, and my cholo Spanish swearing was fluent by the end of the summer. And like a fool, I went back for two more summers after that.
Pro tip: kerosene gets asphalt off your skin. E45 replaces the skin oil the kerosene strips out.