What was the hardest job you've ever had? What made it hard?

Long long ago before pangea broke apart I worked at a fast food joint. I was approximately in my late teens. I remember it being physically demanding and they expected me to go warp speed for 8 hours a day nonstop. It wasn't easy and they expected the world out of a bunch of teenage kids apart from the few adults there.

It is why I have patience and a lot of respect for those who work those places. I've been there and haven't forgotten what it is like.