In teaching, I get to create lessons. I write them out, daydream about them and anticipate sharing them with my students. This is very much like outlining a plot and dreaming about what is to come.
Secondly, I am working with children, having a small hand in shaping their characters. I get to interact with them and celebrate their learning and empathize with their frustrations. While my fictional characters are fictional, I often feel like they are real. I have even more say about how their characters will develop and I certainly feel their highs and lows.
Lastly, in both writing and teaching I get to share some of myself with others. Although I write fiction, it is heavily laced with my own experiences. Now that I have been publishing my writing, others are able to read about this and often respond to me about their own experiences in similar situations. This is very satisfying. In the classroom, I often share my own stories of learning and growing up. My students share their own stories and we have another thread of connection.
And so, to those who say "Those who can not do, teach", I say "You are so wrong!" Teaching is reciprocal and fulfilling if the teacher is willing to put his or her heart into the job. It should be said that "Those who do, should teach!"