During my last couple of years of college, I worked part-time in the tutoring center, mostly on math and physics. Most of my clients were freshmen who were trying to get out of Calc I, but I also had a couple of seniors who had neglected their requirements and needed to pass Business Stats or the like finish things up.

Having a couple of those students come up to me at one of the graduation ceremonies and say, "I wouldn't be standing here if it weren't for you"...yeah, that was a pretty proud moment.