Suki Waterhouse is kicking butt in Insurgent, but even off-screen she’s a powerhouse!

The British model — who recently split from boyfriend Bradley Cooper after two years — works out with celeb trainer Dan Roberts five times a week when she’s in London.

“We do a mix of resistance training with heavy weights, lots of ab/core work and a fair amount of kickboxing,” says Roberts, creator of a the 21-day model-inspired workout Methodology X.

But would you believe Waterhouse’s favorite body parts to train are her abs, core and obliques?

“The ‘Bikini Shaper’ is a toning move that has worked well for Suki and other models I train,” says Roberts. “It works glutes, firms and tones obliques and strengthens core muscles,” he says. Here’s how to get a firm bikini body.

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1. Lie on your side and stretch out, resting your head on your arm. Raise both legs in the air — this will “switch on” your core and obliques.

Photo: Courtesy of PEOPLE Great Ideas/Wong/Bauristhene

2. Slowly float up your top leg, and lower it (this should take 5 seconds).

3. Do 3 sets of 12 reps on each side.

But the key to flat abs is not toning alone. Waterhouse also relies on cardio to keep looking long and lean. “Kickboxing is our No. 1 go-to exercise,” says Roberts. “We do a lot of advanced combat and Muay Thai moves and we keep it real by doing actual sparring. The girl can really fight!”

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