"I wish I knew that teaching was such an exploitative career. Not only are you responsible for the behavior and performance of almost a hundred other humans, but it's assumed you're available to teach up to five distinct preps per semester, often without any resources provided by the school. The amount of work involved in such an endeavor is immense and results in a lot of stress and hardly any time for the self.
"For example, if this year I teach US history and world history, next year I might be asked to teach geography, economics, and psychology, even if I have little background in these subjects. While a challenge is wonderful, there is a point when a challenge just weighs you down so much that you're like a walking dead person.
"Basically, as a certified social studies secondary-school teacher, I can be required to teach any of the subjects within the broad category of "social studies" any semester. This is like a programmer being asked to program in a different language every year. Sure, it's fun, but it's also a huge investment of time and energy."