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.
Shooting weddings is uniquely draining, physically and mentally. 16 hours on your feet carrying weighty kit, putting your body in awkward positions to get the right angle, needing to stay hyper alert so you don’t miss the perfect shot, constantly thinking ahead, all with the added pressure to not fuck things up. I’ve done some really gruelling location work with even longer days but weddings are always the hardest.