Minka Kelly is obviously not a teenager even though she plays one on Friday Night Lights, but most people are surprised when they discover she's actually in her late twenties (she'll turn 29 in June). So what's her secret to staying so young? Working out would be one obvious answer, and you can tell from these recent photos at a gym in Hollywood that she's fairly hardcore about it and doesn't just sit on the exercise bike and watch TV.

A lot of Hollywood actresses stay thin simply by not eating very much and smoking, but that only works with younger skin that can take the abuse. Once 30 rolls around, most of these women look like they're already halfway to 40 (that means you, Tara Reid). So let this be a lesson to any high school or college-aged girls who may be reading this: if you want to have a tight booty like Minka Kelly when you're her age, hit the gym.