If people want to work, all power to them, but going back simply to fill the time always seems a bit sad to me.
I'm a parish councillor, which takes about 15-20 hours a week of my time, and im doing another degree. Any down time between all that im in my homes studio (ie, spare bedroom) making some noise. Im a living example of the old cliche, I dont know how I found the time to go to work.
The other problem is that im past 55 so gone are the days when I can sign a 6 month contract BGing for £125k. That earning capacity is well behind me now, and having been there in the past Ill be buggered if I'd work now for minimum wage out of sheer principle, so my working days are done.