You ride harder than I do but I don't think you are pushing it too hard.
Sounds to me like you still got plenty of that old "Swagger" left!
I ride with 7 or so twenty and thirty year olds and I ride harder and longer than any of them, but I have a regimented work out routine and they don't. They are not actually in great shape they are just mostly young. I am more careful about what I eat and don't eat and it sounds like you do too.
I was feeling a little washed out a few years back, saw the Doc, told him the deal, he hooked me up with some good B-12, Multi Vs and some stretching exercises,.. and basically told me the same thing that Razzman said, that was the ticket for me.
Again, "Word" to what Razz the Man said.
I believe it to be the gospel truth.
We can still roll after 50 but we have to do it a little smarter not harder, you know what to do.
I found that for me, going through a good stretch out before and after I ride also helped a little all the way around. At our age I think we need to warm it up good before and after we do some serious cooking but once warmed up we are as good to go as anybody.
The younger riders should actually do some of the same things but because of their "immortal youth" they just don't feel it yet,... but they will.
The better they take care of themselves now the longer and better they can ride later.