Do you know how I know I'm old?

The other night, a friend called and we had stimulating conversation.
About medication and supplements.
Yes, yours truly has officially entered that stage in adulthood when you stop being cool and start worrying about your health.
Which was the next topic of conversation.
How did this happen? This didn't just sneak up on me, I know I've had these conversations before. But usually they happened when we were being cool and sarcastic about it. Like having deep conversations about the state of the world and how totally messed up it is, then a slight segue into some new vitamin regimen that will supposedly keep us young and beautiful forever, then laugh at the elderly and how they have nothing to look forward to but conversations about ailments and medicine, then back to being awesome.
I guess I don't feel sad about it. It was an interesting conversation. And it's not like we were complaining about how kids these days don't know what respect means (which they so obviously don't).
Damn kids. They better just stay off my lawn.