My doctor had a renowned research record, retired at 68 but got bored, and went back to work. Whilst I was in hospital, I got to observe him throughout the work day.

I don't mean this in a creepy way at all, but I got the impression the greatest source of joy was hanging around with younger people. A hungry grad, a cleaner, a nurse, male, female, whatever.

I'm sure he enjoyed his peers as well, but I could detect a shade of boredom of those interactions, which inevitably had stress and responsibility attached.

I think what I'm trying to say is that work isn't just about challenge, it's about socialization and having fun. And one of the greatest benefits of being financially independent is being able to navigate to those kinds of moments without the pressure of being on the make.