Studying feels like hard work when you are a kid, but it's kind of a joke how easy and non-draining it is in retrospect. Doing actual work is just so much more taxing.
I think it's due to how linear studying is. Actual work on the other hand can be quite unpredictable, it's a bit like a monster of the week show where monsters are incidents, bugs, and unreliable leaders. And there's also linear work on top of it.
