It may seem that celebrities know some magic secret to a perfectly flat stomach. But the truth is, many of them put in grueling workouts, week in and week out, to keep their tummies toned. Here, we've rounded up seven things stars and their trainers have said about what it really takes to sculpt such enviable abs.

On kicking it up a notch...

"I watched my body transform over a week of intense training [for Charlie's Angels]—some days doing upward of 1,500 to 2,000 kicks a day. Kicking, kicking, kicking for eight hours. All of a sudden I had six-pack abs. It was painful. I would not recommend that anyone blast their body like that. It was an intense, physical challenge. But it woke me up to my own body and what it was capable of." —Cameron Diaz to USA Today

On the best belly-blasting move there is...

“Being in a plank position and tucking your knees in, like ‘Run, run, run!,’ then taking your legs wide and coming in at a diagonal with your knee and then out. That’s the best one. I would do this until exhaustion—and to music, for sure.” —Jennifer Lopez's trainer, Tracy Anderson, to Health

RELATED: Take the 30-Day Core Challenge with Tracy Anderson

On prepping for a bikini photo shoot...

“I do eat the whole time, but I work out a lot, usually two workouts a day for two or three days before. I'll go on a 10-mile bike ride or something, and then I'll come back and work with a trainer. I do pretty intense workouts in the gym. ... I hate running. I love sports—I could play flag football or basketball all day long—but ask me to get on a treadmill, I hate it. But I've been doing sprints now; I sprint for a minute, I've got a 30-second break, and then I sprint for a minute.” —Hannah Davis to Health

On keeping things interesting...

We always end every workout with a ton of abs work. [Jenna] likes to slide on the floor instead of typical crunches, so we’ll work them in a million different ways—dancing and booty popping planks to bridges, all kinds of stuff. We mix it up so every workout is different.” —Jenna Dewan Tatum’s trainer, Jennifer Johnson, to Shape

RELATED: 24 Fat-Burning Ab Exercises (No Crunches!)

On chiseling that core...

“First and foremost you have to train your abs on all three planes. You have to train them forward and back with something like a crunch or double crunch. You have to train your abs laterally to hit the obliques with something like a dumbbell side bend. And you have to train your abs on a rotational plane—your transverse abs—and you can do that from a seated trunk twist." —Lady Gaga's trainer, Harley Pasternak, to Rodale Wellness

On the power of the plank...

“The plank is a favorite, but we take it to another level opening and closing the legs like scissors while at the same time raising and dropping the hips! So not only are you strengthening the core but also timing the hips, thighs and waist. [We also do] the trunk twist along with a back row using the bands. The benefit of this exercise will give you flat abs and coke bottle obliques while removing those fat handles from the back and arms.” —Kourtney Kardashian’s trainer, Don Brooks, to E!

RELATED: 5 Exercises for Rock-Hard Abs From Gwyneth Paltrow's Trainer

On sweating off baby weight (literally)...

“After I had my babies and was struggling to lose that last bit of weight, I had to challenge my body in a different way; hot yoga was key. You sweat so much, you lose poundage. I dread it every time but afterward I’m grateful for it.” —Rebecca Romijn to Health