69. My wife, 65, and I just rode our first tandem double century, STP. Great success! We are both in almost perfect health. It's mostly luck. One sees folks our age and older hiking, climbing, riding, whatever, and it's mostly luck. All the hard work and perseverance in the world doesn't trump luck. Accidents, injuries, genetics, and many other difficult and traumatic events wait for us. However, hard work and perseverance definitely improve one's luck. A fall is less likely to result in injury. Low BP keeps strokes away. Low visceral fat keeps all sorts of problems away. Life is mostly about choices, and unfortunately we can't know the result of our choices until it's much too late. I think that problem is what societal institutions are supposed to help with. Unfortunately the ones we have today that aren't completely useless are frequently completely wrong.
10 years, we hope to still be riding and hiking, though with much slower friends.
20 years, we hope to still be alive, but will probably not be having much fun, global warming having flooded our home since 1975.
30 years, we hope to be dead.