But celebs have to be camera-ready at all times, whether it's in the parking lot outside of Equinox or at the top of Runyon Canyon.
From adorably stylish workout brands like Lucy and Lululemon, to old standbys like Nike and New Balance, find out what Reese Witherspoon, Jessica Biel, Katy Perry, and more chose to wear during their sweat sessions:
Celebrity Gym Style
Of all the things we envy about celebs, their incredible physiques top the list. See what stars like Jessica Biel (a Nike fan!) wear to stay inspired (and look paparazzi-ready) during a workout session. By Karen Brooks
Lucy Impact Knee Pant
Celeb Fan: Reese Witherspoon
Seemingly age-proof Reese Witherspoon keeps her body and mind young with regular runs. She owns these Impact Knee Pants from the fashion-forward fitness brand Lucy. A dedicated fan, Reese also recently picked up some criss-cross tanks and a pair of yoga pants from the brand's Santa Monica store.
Under Armour Quickstep Shorts
Celeb Fan: Carrie Underwood
Life may be one big Carnival Ride for Carrie Underwood but staying in shape is no easy task. The superstar works out with a trainer, running, kickboxing, lunging, squatting, and doing moves on a stability ball. To help her get through the grueling routine, she suits up in lightweight, breathable Quickstep shorts from Under Armour, which help show off those toned quads.
So Low Ruffle Foldover Pants
Celeb Fan: Cameron Diaz
The legendary legs of Cameron Diaz are often skiing, snowboarding, surfing, or hiking. But on those days that they're lounging (or hitting up an actual gym) Cameron chooses So Low's Ruffle Foldover Pants.
Nike Blaze Mid Sneakers
Celeb Fan: Ashley Tisdale
When it comes to working out, Ashley Tisdale says, "Bring it on!" Whenever we see the "High School Musical" star leaving her favorite hip haunt -- the Equinox Fitness Club in West Hollywood, CA -- she's usually sporting a pair of limited-edition Nikes like the Women's Blaze Mid shown here.
Lululemon Run Swiftly Tech Tee
Celeb Fan: Jennifer Garner
Jennifer Garner gave up her amazing "Alias" physique to become a mom, but she's done an enviable job of whipping her bod back into shape. Whether working out with her trainer or going for a run, she's a fan of Lululemon workout staples like this body-shaping Run Swiftly Tech Tee.
PH8 Side Inset Legging, Tank
Celeb Fan: Katy Perry
While other stars prefer sweating in out in the gym, Katy Perry likes jumping rope -- a habit that must be handy while she's on tour. As for her workout wear, she chooses the Legging and Tank Top with Side Inset from PH8.
Lululemon Groove Pants
Celeb Fan: Katie Holmes
Despite the flack she got for running the NYC Marathon, at least Katie Holmes participated in style. For the five-borough trek, she chose Lululemon Groove Pants (there's a label hidden inside the waistband to write her name on) and a Power Y Tank (with a built-in bra, so she didn't have to wear one with it). Her workout look is just as trendy as her latest hairstyles but her fitness routine is hardly as short.
MBT MWALK Sky Sneakers
Celeb Fan: Paris Hilton
Cardio, squats and the thigh machine are said to keep this hotel heiress/actress/businesswoman in shape. But even when she doesn't have time to get to the gym, Paris Hilton manages to squeeze in a workout-thanks to her MWALK Sky sneakers from MBT. Designed to shape and tone muscles in her legs, back and buttocks, she's working out whether headed to the airport for her cross-country jaunts or just running errands in LA.
