Harley Pasternak's 6 Star-Tested Tips for Looking Your Best at Any Age

The celeb trainer and PEOPLE.com blogger reveals how Sandra Bullock, Halle Berry and more stay forever gorgeous

1. Don't Make Your Fitness Dependent on One Machine/Person

Who gets it right: Sandra Bullock, 48
It's hard to believe Demolition Man was 20 years ago, since Sandra Bullock looks almost exactly the same at 48 as she did then. She didn't achieve the body she has now by doing the same tired routine every day! Bullock likes to mix up her workouts, doing everything from Pilates to kickboxing. Our bodies adapt to a regimen within six to eight weeks, so if you don’t mix up your routine, you will plateau.