Remember Kim's Workout Tape? Break a Sweat Down Memory Lane with These Celeb Exercise Videos

QUIZ: How Well Do You Know the Chiseled Abs of Hollywood?

One of the most significant moments of childhood is developing your first celebrity crush – whether Titanic or the “Bye Bye Bye” video was the source of your giddiness, the experience is formative.

While crushes become more sophisticated in adulthood – you’re more interested in, say, a man’s intellect, or how he treats the women in his life – some things stay the same: namely, a dope body.

We’ve rounded up Hollywood’s hottest abs. Can you identify the heartthrob they belong to?

Cassey Ho: Meet YouTube's Fitness Star

Watching YouTube fitness star Cassey Ho smile as she does a million squats (at least that’s what it feels like if you’ve tried her most popular video, Call Me Maybe Mighty Squat Challenge), you would never guess she grew up chubby.

“There were some mean kids back then, and that affected me,” says the bubbly host of YouTube channel Blogilates, which has 1.3 million subscribers. “I became conscious of my body at a young age.”

Jen Selter: How I Became an Instagram 'Belfie' Star

When it comes to hitting it big on social media, bum’s the word!

At least that’s the case for the 20-year-old New Yorker Jen Selter, who has squatted and lunged her way into the hearts and Instagram feeds of folks around the world thanks to her “belfies,” or butt selfies, she posts online.