When I was in my early and mid teens, I couldn't wait to get the hell out of the youthful stage and into the more stable mode of adulthood, aka past 30. Now, at 20, I wish I could stay in my late teens/early 20s forever. I'll admit, its kind of nice having very few responsibilities and not having to worry about having a plan and the ability to be completely spontaneous. Who knows. Maybe when I'm 40 I'll look back on my twenties and be glad that they didn't last forever.
I've also come to realize that, in the gay world, turning 30 is like a death sentence. Its seems that as soon as you hit that number, you're no longer sexually viable or "young enough" to be worth being around by the younger, prettier crowd. Many guys my age have a "Nobody over 30 policy", as if older guys have nothing worthwhile to add. Maybe the big reason gay guys are so obsessed with body image is because we want to hold onto that ideal image of youth and beauty.