When I'm asked (a very common question in the USA): "What line of business you're in?", I usually answer: "I'm in the business of helping people."
Helping students succeed (and enjoying their success) is the key motivation that drives me to do what I do (and hope to continue doing for years to come...).
Courses, departments, technologies, programming languages, ..., come and go. The essence of teaching -- reaching out to students, connecting with them, and taking them from point A to point B -- remains unchanged. At the end of the day, whether you're a teacher, social worker, nurse, medical doctor, or play any other role in the lives of others, it's all about people acknowledging their interdependence and helping one another.