"How do I love thee, let me count the ways" .... I don't love just one thing "the most" about teaching. I don't know if I can pick just one thing; instead I'll pick my top three.
I love the light in the eyes of the students as they suddenly understand something they couldn't even grasp before; it's that "Aha!" moment which sparkles out when something we're covering in class suddenly "clicks."
I cherish hearing that "least-likely" student say that mind-blowing "thing" in response to a question I ask...and suddenly the other students perk up and look differently at the one who bravely spoke his/her epiphany aloud.
I relish the moments when we're discussing literature and get so wrapped up in the conversation that even those students who usually have their eyes glued to the clock are surprised when the bell rings.
If I can remember these things I love on the days when I wonder if Christmas Break (or Summer, depending on the time of year) is coming soon enough, I will have the inspiration to continue further on and further up.