Why Do You Teach?

I first read the article last year. It was included in the Form 5 July Test. I put it away somewhere to reread it and only came across it again recently.

It's written by Peter G. Beidler and my favourite paragraph is this:
"Certainly I don't teach because teaching is easy for me.Teaching is the most difficult among the various ways I have attempted to earn my living... For me, teaching is a red-eye, sweaty-palm, sinking-stomach profession. Red-eye, because I never feel ready to teach, no matter how late I stay up preparing the night before. Sweaty-palm, because I am always nervous before I walk into that classroom, sure that I will be found out for the fool that I am. Sinking-stomach, because I walk out of the classroom an hour later convinced that I was even more boring than usual."

True isn't it?
When a lesson goes well, you feel on top of the world. But when it doesn't, it's thoroughly soul destroying. You then ask yourself: Why do you choose to become a teacher? You are horrible at it!

Why am I still a teacher then?? (Apart from being bound by contract) the rest of the article seems to partially answer that question for me.