I mentioned this recently in a thread about funny life charts:
I used to have a fair amount of social anxiety when I was younger. Now that’s mostly gone because I no longer give a happy crap what most people think of me.
However, ordinary things that I never thought twice about when I was younger now give me anxiety, like climbing ladders (Is this thing sturdy enough? Can the old joints take it?).
Never mind.
My kids couldn’t fathom that there was a time when TV program ended every day - like, just ended with the national anthem and color bars, then static - and didn’t start again until around 6 the next morning.
Also, I was joking with a cashier that it sucked being told I look like the before in a plastic surgery before & after because I look like the before picture of Jennifer Grey (because I pretty much do, only if Jennifer Grey had, um, spread with age); he looked at me blankly, and I explained, "the actress from Dirty Dancing. Guy literally thought I was telling him I looked like a porn star.
The two main things I notice are
When something goes wrong physically, my first thought is, “so this is the new normal?”
When I don’t meet my own expectations, I just adjust them downward so they fit.
Technology and popular music and television started passing me by in the early 1980’s so that isn’t a marker of old age.
You know you’re getting old(er) when…
…you have to keep increasing your OS system/font-size in order read online content.
I’m up to ~1 character per screen. Gotta scroll 3 times to read “cat.”
This might make you feel a little better. My 25 y.o. daughter is an unashamed member of the AARP. She found out that they give great discounts and have no age limit. Happily reads the newsletters. So not everyone in the AARP is old.
I have been working at my job longer (35 years) than most of my co-workers have been alive.
One once mentioned his age in conversation. I said, “when you were born I had already been working here 8 years.”
By his reaction you’d have thought I stated that I fought at Gettysburg.
mmm
There are, at last count, at least 10 staff members (Faculty & Support) at my school who are former students of mine. For the last 15 years or so, every new batch of students has one or more children of former students. I’m retiring before I start getting grandkids of former students.
FtGKid2 has been in on the ground floor of startups several times. The current one is doing quite well. He’s employee #5. Since he’s a senior, experienced person in the company, he’s referred to as “The Old Man.” Not even 40 yet.
You know you’re getting old when your kid is “The Old Man”.
Getting the first piece of junk mail from a funeral home or cemetery.
I’ve been getting mail from the Neptune Cremation Society for a couple of years. 
You know you’re getting old(er) when…
…your grandparents who you lived with were born before Coca Cola was formulated and the electric light bulb was patented.
During WWII my dad was the third oldest in his squadron after the Old Man and a cadre Chief who’d been been in the navy long before the war started. He was 24 and his nickname was “Pops.”
You know you’re getting old(er) when…
…news stories casually refer to events around the time of your birth as happening in “the late 1900s” rather than even specifying the decade. Just heard that in an NPR piece this morning.
One that sent a chill up my spine: The doctor uses the phrase “rest of your life” even though NOT imparting bad news. Such as “You’ll be on this medication for the rest of your life.”
I have too, BUT I requested information from them a while back.
I have acquired PLENTY of wisdom. The only problem is, I can’t remember most of it. Sit there going, ‘and another thing about that, ummmm - let me tell you what we, umm, thought back then…ummm’. I bore myself!
It’s when Debbie Gibson starts advertising reverse mortgages or Medicare Advantage plans that you’ll know things are really bad!
I’d go with ear and nostril opener.
And that’s assuming either still exists when she’s qualified for them.