It's not the most artfully worded question, but it's worth asking.
I never really thought about all the things I do in a school day. But now that I'm working with a student teacher, and having to help her prioritize her activities, I'm realizing how much there is to do that doesn't involve being in front of the class delivering instruction.
I utilize my "down time" at school. I don't relax, work on a puzzle in the staff lounge, read the newspaper, etc. No, I'm getting work done. I'm grading papers, inputting grades into the computer, communicating or meeting with parents, filling out disciplinary paperwork, writing tests or quizzes, planning lessons, taking roll, completing special education paperwork, checking up on students (because of grades, traumatic events, etc), making copies, meeting with vice principals, and myriad other tasks that don't directly involve my being directly in front of students.
What I've determined is that only about half the job of being a teacher is teaching. If it's a field you're considering, you can't focus solely on your presentation of material to students. There's much more to it than that.