I didn't start to feel old until people started treating me like absolute shit.
When I was in my 20s I'd like to have conversations with anyone. You could be 80 or 8, didn't really care. I saw people as people, that's just how I was, and if you were people I wanted to get to know you. This was apparently OK if you're in your mid-20s, and 15 years ago when society wasn't yet in a persistent state of low-level panic.
Exact same person except now mid-30s and balding and ugly, and the same behavior -- no ulterior motives, mind you, just saying hello to strangers -- and I'm apparently some super-creepy weirdo, someone ought to call the police. Because I'm ugly and said hi and that means I'm Jeffrey Dahmer or something. Also, the world has changed and apparently that means you STFU and mind your own business.
Well, be glad, because I learned. I know my place now. When you're old and ugly, people don't want you to exist. Like most people my age or older, I avoid talking to others now, as much as I can manage.* Killing myself would be ideal, I guess, but failing that, it is my obligation to society to be as invisible as possible. No wonder old people are committing suicide in droves, but I guess that's a good thing because it's what everyone wants.
I guess some folks who experience bigotry are all "welcome to my world", but if not, don't worry, it'll happen to you too.
*And people here are constantly whining about how lonely they are. Huh.