I have some "real" medical things, but I am in better shape than most other 56 year olds. Since I have been active since I was 25, I can't say that I am in better shape than I was then, but in a way, I think I am. Back then, I was a gym rat, and that lasted until I was in my mid forties. I was so sick of that, that I had a kind of "lapse" in my fitness/health when I was 45 and I certainly was on my way to being fat, forties and unhappy/unhealthy. Now, I am outdoors doing my sports most of the time, even in the winter. My lifestyle has changed in that instead of getting up at 5 to go to the gym, so it doesn't interfere with the rest of my life, being active IS the rest of my life.
I am not as fast as I was on the bike 2 years ago; on the other hand, I am still on the bike, and in the end, who cares if my average is 16 or 15? I started running this year, too, which is not easy for me, but it's sure a hell of a lot easier than it would have been for me ten years ago.
My dad is 85 and still active in the sense that he works 3 mornings a week and has a social life that rivals most. He's never been into physical activity (my mom was the athletic one), but I only hope I can be like him; out in the world and mentally engaged at his age. My other role models are the members of my cycling group. Some are 70 and participate in endurance stuff that put me to shame. Some of them have battled serious medical stuff and they always get back on track, because it's part of their lifestyle.