Teenagers continue to make me feel old ALL THE TIME.
One of my friend's is in his early 20s and still lives with his parents (and is generally an unemployed slug), and for some reason his 14 year old sister often ends up tagging along with us (usually because his parents usually only agree to give him money if he takes Trish with us), and SHE really makes me feel old.
It is never the AGE of people that make me feel old, it is the YEAR they were born in. Now there are teenagers (like Trish) who were born in the 90s.
On an aside note, I show A LOT of signs of aging myself, even at 28.
I stopped listening to new music years ago.
Almost all my friends are married now.
I have begun to get gray hair.
All cars produced after I graduated high school (1995) still seem "NEW" to me, because I remember when they came out. Oddly enough I have been driving Pre-96 models my entire life, with only one 2 month exception. (In order I have owned vehicles from 1984, 1988, 1983, 1986, 1988, 1995, 1983, 1984, 1999, 1989, 1983, 1975, and 1991. I still own the last 4 on that list).
I haven't purchased a video game system since the Dreamcast, and that one I got after it was discontinued. I no longer own any consoles at all, other than a couple of the joystick ones (never used), and an Atari 800 (also never used).
I no longer rush out to the electronics store/auto parts store/rpg shop/etc every time I get paid. Heck, I haven't bought a single stupid automotive "upgrade" for about 5 years now (5 or six years ago I built a car MP3 player before they were common on the market).
I haven't missed work because I partied too much in at least 8 years. I haven't even called off in six or seven years.