Happy Birthday! I've got a couple months until I celebrate the same. And honestly, I wouldn't go back to my early 20's for anything!!! I feel like I finally know who I am, what I want out of life ... and I'm excited to spend my 30's enjoying that.
Sure, as someone said above, the early 21-ers will think we're old ... but aging is something none of us can get out of ... they'll get theirs too.