Working with young people. Not tiny kids who can't string a sentence together, but from say the ages of 8-18. Helping the more troubled ones, whether that's from a background of poverty or just because they're a typical angry teen, to become a decent human being. I suspect that's an incredibly rewarding thing to do, it just doesn't pay enough to be a true goal in regular life.
Or teach learner drivers how to drive for fun, and the basics of car physics so that when they pass their test they can go for a hoon but have some idea of what's going to happen. Truth is I've looked into this, but I struggle to make a business case for it. Lottery win would sort that out though.