Here's something I did last year, which I'll be doing again in a few weeks.
Back in high school, I had a really great math teacher. He really created excitement about the subject, and he always had extra time to teach extra stuff to us. Just a really cool guy who'd show us Monty Python videos sketches and then some interesting math problems. It was really night and day when compared to for instance what came later at university. I found myself practicing a lot of extra math for no reason. Plus of course it made actual math class a breeze.
Three of us went to do a math contest each year, and in the final year - he was retiring, we were graduating - we won the contest.
So I've arranged for the other two to fly over to me and we're going on a road trip to see him.
If you're wondering whether he's bothered by it, I think he'd say that was the whole purpose of teaching, to show young people some interesting stuff and motivate them. The guy even sees his old "kids" who are now in their early 60s. He's mid 80s.