There are those things that you deal with that make you realize, kind of out of the blue, that you're no longer as young as you used to be.
You find a grey hair - in your eyebrow.
You do about an hour's worth of yard work and your back feels like you've been working all day. (Believe me, when *I* start to think about how good a massage might feel, something is definitely wrong.)
Or you run into your neighbor when out walking the dog and decide to spend the evening on your neighbor's deck having some wine and hanging out. And as you start to feel tired, you gradually make your excuses and head home, where you turn on the TV and realize that it is just barely after 10pm.
What's worse is that I'm pretty sure that the three or four glasses of wine I had over the course of four hours are probably going to give me a hangover in the morning.
Of all of the things that I've lost over the past 20 years, the ability to fend off a hangover is definitely one of the things I miss most.