Until you hit 32, which I just did, and decide that there's no point in holding on any longer. *frown* I'm still adjusting to this whole "thirties" thing.
I always hated the 9's (29,39,49) 'cause I "felt" like people were thinking "29, yeah right, she's really 30" so I looked upon the next year as quite liberating. The jury's still out as to how I will feel when/if I make it to 60 in less than 2 years.