I always assumed it was because she never seemed to overwork herself. She seems like someone who takes her time doing things. So I'm sure she has lots of time to work out and do beauty regimens and what not to look as great as she does. Plus she probably has really good genes.
My theory is that after performing Hollaback Girl enough times, she actual EVOLVED back into a high school cheerleader. So in reality now she's only in her mid-20s.
She has good genes for sure, her skin is absolutely flawless and doesn't look weird like most women after they go under any type of surgical procedure.
