All teachers are, in effect, missionaries for their subjects.
I might consider going into that field just because of a teacher. Since the effectiveness of teaching is proven by its results with the students, it seems appropriate to begin with their comments about the influence a teacher can have. Your teaching responsibility is commonly defined as imparting concepts and problem-solving techniques. Students, however, see instilling motivation as a primary teaching function, in the sense that everything else depends on it. But when you feel that the professor cares about what you're doing and whether you understand and whether you're enjoying the subject, then it just makes a lot of difference.