In 2002 I retired as a self employed CPA, since 1967, after finishing school and going to work in 1961. I kept my existing tax clients. Had a real busy tax year in 2005, lots on varied work. This got me revved up again and when I saw an ad for a CFO at a small country hospital, I went to work there. Probably the most enjoyable 5 years of my work life. I was older than anyone there, other than one doctor. However, by last spring my mind was starting to slow down. Things I had done for 45 years, I sometimes had to stop and figure out what to do next.
Retired again about 4 months ago (except I guess I will keep doing my tax returns). This time I pulled out my guns and reloading stuff and I have really enjoyed that. Otherwise I don't know what I would do with my time. I guess it would be internet to reading to tv and back around again. Physically at 73 I can't do near what I could even a few years ago, and I really don't have any health problems and take no medications of any kind. Probably still have a long time to go as my dad is 97 and my mother 93 and still live by themselves.