Funny, I didn't think it was something that could sneak up on you.
For a good part of my life, I've been thrashing around, trying to figure out what it is that I'm supposed to be doing. I've had jobs, and I had a career, and I'm having a great stint as a parent just now. I've dabbled with writing with some success, but I've come to realize my heart's not in it. I like it, but it's not something I want to spend all my time doing.
So after years of dithering, it really does come down to the most obvious thing, teaching. I find it fulfilling in ways that software development never approached. I don't think this sense is comparable to youthful enthusiasm, the kind that evaporates when it makes contact with reality. I'm not that young, and I have an understanding of the day-to-day grind that can comprise a lot of teaching.
But it doesn't have to be that way. I come away from my religious ed class on Monday nights with a tired voice but mentally recharged; it's the same way when I get home from the monthly thyroid cancer support meetings. This is good work.
Is it strange to find a vocation in my mid-forties? Better late than never.