Skiing after 60

As I was skiing yesterday, I was wondering when the “next shoe will drop;” in other words, when am I going to start slowing down a bit. Until now, I’ve been able to ski faster and more than ever before (if we count in days and vertical drop.) Part of it, has been the new equipment that makes it so easy, and part of it has been my rather good physical shape (regular running being the number one reason.) In addition, there’s a subtle system of compensation that allows me to still do a lot with less resources. I must be shrewder, I must be “cheating” a lot and I expand just the minimum amount of energy required; isn’t that wonderful? Now, I’m wondering when all that good stuff will start going south in a measurable way. I guess it will be gradual, before my bones become brittle and my muscles too weak… It’d be nice to see a little light on the dashboard that says “Check Engine” or something like it. If you happen to be in your sixties, or better yet in your seventies, could you please give me a preview of some of the milestones I should expect to encounter along the way?