I believe it is all in the mind. If your mind is weak---, well, no need for me to finish the sentence.
Let me quote a question I recalled from somewhere: "How old would you be if you didn't know how old you are?"
It irritates me when I hear someone says: "I am too old for this". Or, "You are too old for this". What the hell! Go away! I don't need your bad influence.
If all the people you "hang around with" act as though they are a hundred, you probably act the same whether you know it or not.
The younger you think, the younger you act, and the younger you are.
A lot of people drop out of activities they did when younger. Doesn't matter what the activity is, to continue the activity forever takes determination, discipline, tenacity, etc, in addition to an enjoyment of the activity. It really doesn't have much to do with age. If one doesn't have the will or determination, he won't last. It could be ping pong, golf, or, hey, even marriage. It has nothing to do with age.
I have been for years going to the gym several times a week in addition to my Uechi practice. To be honest, quite often I had to consciously shut my brain off in order to finish all my gym routines. Nothing to do with my age, it just gets boring sometimes but I am not a quitter. So, I modify the routines, I make it harder sometimes and easier other times. I don't see quitting the gym any time soon. Besides, those skimpy gym outfits sure look good on those young women.
Same with my Uechi practice. I love the art and I enjoy doing it to no end, but let me admit, some days I just don't feel like doing it. But, I still do it regardless. I can't remember missing one regular Uechi workout in the last ummty years except when I was sick or on vacation. Yes, some days when it gets bad I had to do katas the Taichi way-- soft and slow, but most of the time I still go at it full blown. Yea let me also admit, I can't do 3 times each of the eight katas non-stop anymore, can't do those spinning kicks or high kicks anymore either due to knee injuries, but, so what?!
For those who quitted, don't blame the age.
I started in the Mattson Academy back in 1965. I don't feel a day older than 40. Chronologically I will be 71 this Thanksgiving but it means absolutely nothing. Huge Hefner is still my hero. So there.