I retired the first time from the US Air Force after 21 fun-filled years. Seriously, I had really great assignments and saw a fair bit of the world. But my last assignment was in the Pentagon, where it was 12 hour work days and a 75 minute commute (each way), so I just got tired of not having an actual life. Hung it up and when they took my photo for my retired ID card, the photographer said it was about the biggest grin he had ever seen.
I had no real skills at that point, since I had always been a generalist, but I had often been told I was good at explaining complicated things. Based on that, I decided to try being a technical writer. That was a good decision, and I wrote the documentation for software for a number of years. I always considered that a particularly great career, since nobody ever reads that stuff anyway, so it took most of the pressure off me.
After a number of years doing that, the company where I worked got bought by another company, and about 65% of us got laid off. I was 55, and decided that was a good age to retire.
But "retirement" is a really slippery word. Since then, I have put in at least a few hours a week as an independent, freelance consultant. What's funny is that my consulting is related to the beer business. Beer has always been my hobby, and I got good enough that I'm reasonably well known. Nearly everything I make in this line goes into an independent 401(k), and I show just enough of a profit that the IRS doesn't classify it as a hobby.
It's a great life. I live in southwest Ohio, not far from Cincinnati. Having grown up in Brooklyn, New York, I think this quieter place is just fine, thank you.