I know a guy who was at the ‘required’ retirement age with 30 yrs at his company. They re-hired him as a contractor....they did not want him to leave as his work has been so advantageous to the company all those years, and he didn’t want to retire. They tweaked his responsibilites just a tad...(no overnight travel) and both are very happy with the arrangement. He wants to work as long as he can and that could be decades!
My father is 90 and still chopping firewood. :)