If you've never taught then you do not know how true this is. You have to get together worksheets or a film or something constructive for the kids to do so that they aren't bored and drive the substitute crazy. Sometimes that's a lot more work than just being there suffering through and teaching. Many times I have gone in sick just because the task of getting together something else for the students to do was worse than actually going in.
Yesterday, I had to figure out assignments for all of my classes since I would not be at school today. Even though I'm battling a cold, and would like to stay at home in bed, I actually have something I'd much rather be doing today. Most teachers are going to think I'm crazy for wanting to do this, but I'm actually very excited. I'm going to a professional development workshop today. It's a topic that I love, and something that my master's degree was centered on, but I do expect to learn more about this area of the topic.
Unlike most of my students, I love learning new things. I love being able to sit and listen to an expert and take notes. Honestly, if I could be a professional student and make decent money doing so, I'd do it in a heartbeat. However, unless I go back and get another master's degree, I think my days as a student are over, except for professional development. Grant it, I'd love the chance to go back and get a degree in library science, counseling, American literature, or theology. If I were independently wealthy, and never had to worry about money, I'd go for degrees in all four, and maybe a few languages too. Until I win the lottery, those are just dreams.