I don't think we can know another's intrinsic motivation. Your T has probably helped a lot of clients and learned a great deal and felt a great deal of satisfaction from working with them. T's are kind of the other "half" of us; we want to work on us and they enjoy helping us work on us. What motivation does a parent or friend have? Why are you friends with X? You like them, that's why. There don't have to be reasons other than what makes sense to you.