The worst part of being a teacher is that every day is a hard deadline- even if you don't feel like working (or working hard), you have to get a lecture out.
The second-worse part of being a teacher is coming up with cool and interesting homeworks that are (especially for the intro courses) substantially different from semester to semester.
Right now, I've got to create a new homework for both of my classes, and I'm tapped out. Everything I can think of is either too easy, too hard, or requires topics we haven't done yet. Even trying to pillage ideas from other books isn't helping, because I've already used all of their good ideas.
I have until tomorrow in one class, and Friday in another. I hope I think of something by then..