I think I turned the corner to "old" this year, but I'm hoping its temporary.
I'm 61, and I've never felt old until this spring. A combination of work, minor family emergencies and increasing laziness resulted in me getting almost no exercise from about Thanksgiving until a couple of weeks ago. I'm usually pretty active and at least lift and hit the gym a few times a week in winter if I don't ride, but this year I did squat for three months. I've gained 20 pounds, which I can take off, but I'm stiff, inflexible, my joints hurt and I find myself thinking things like, "I don't really want to watch a 'Friends' rerun, but the remote's way at the other end of the couch . . . ."
I'll get it back--I've already started working on it. But it's a lesson for all of us: Once you reach a certain age, apparently 60 for me, you can't take it for granted anymore. I have a LOT of work to do to get back where I was. It's a lot easier to STAY there than to GET there.