I have a colleague who is sixty nine years old. He just finished his 39th year teaching, and last year he was awarded the researcher of the year award by my college. I've always been impressed by his passion, energy, and enjoyment at being an academic going into his fifth decade in the university. Now I know why - compared to his father in law, he's still a relative rookie.
The New York Times has an interview with said father-in-law - Professor Ernest Kurnow. of New York University. At ninety six years of age he still teaches a class or so a year at NYU. That's right - at ninety-six. I'm not that ambitious - I only plan on doing this gig for another twenty five years or so.
Then I'll retire at the relatively tender age of seventy five.