I am 47 (almost 48) and so not really a 50s person yet, but edging closer all the time...
I still work, probably 70+ hours a week. Own 3 companies. I love working. What I managed to do is arrange it so I get paid to do what I would probably do anyway. For example, I will go out and meet with people out on the fincas to show them around. I end up riding horses. One of the workers tack them up and clean them up afterwards. But this is work.
I spend time reading about the tropics, wood, forest, biology, etc. Again, this is my job, but if it wasn't I would probably still do it.
I also spend time doing business deals - again, I enjoy it, doesn't feel like work. I have experiences and write about them for our website - they draws people, it doesn't feel like work.
I guess if I was really working I might plan on retiring, but until people figure out I am not working... I guess I will keep doing it.