Some people can't wait to grow up, and other people want to stay kids forever (at least maybe early 20's). That being said, time marches on whether we like it or not, and either way, some things get better and some things get worse.
Water Parks - now all I see is piss in the pool and a gaggle of judgmental teens.
My birthday. It's not that I hate it, it's just that I don't care about it anymore.
Going to the mall. I used to like browsing stores, but now I just want to get what I need and go.