I recently changed my job responsibilities to include technical instruction and I have to admit, that this is more enjoyable than sitting in front of a desk all day long. During a recent conversation with another instructor, he pointed out to me how much he enjoys what he does. I have to admit that standing up in front of a classroom did give me a bit of pause initially, I have found it to be rather enjoyable to describe how things work and demonstrate them.
He said to me, "My job is great! I get to spend all day long in front of students who have paid for the class and are usually genuinely interested in what I have to say about Open Source software!"
Sure, there are things that are difficult about teaching - students that are not interested in the material, classroom and hardware issues, typos and incorrect information in the instructional materials, etc. - the satisfaction you get from seeing the faces light up with comprehension is well worth it. While it's true that standing in front of complete strangers gives most people the terrors the same way that standing in the middle of a highway and realizing that a tractor trailer is about smash into you, I feel comfortable walking into a room of complete strangers and saying hello and diving right into the material.
Perhaps I feel comfortable with that because I know the students have paid a fee to get into the classes or perhaps it's because I know the material from having workd with the software for almost ten years now. Perhaps it's simply the motivation that the students will learn something and knowing that in the process I will also learn a lot.