So This Is How Margot Robbie Got in Shape for I, Tonya

Think your job is demanding? Margot Robbie's latest role as Olympic ice-skater Tonya Harding in I, Tonya didn't just require her to look the part—the actress also had to learn how to skate and improve her fitness to keep up with the physically taxing scenes.

"I spent a lot of time in the gym, trying to build muscle mass for I, Tonya," Robbie told Body+Soul before the Australian premiere. "Weights, mostly, and lots of sit-ups" formed the basis of her workout routine. "It's all the stuff you know you're meant to do, but just can never be bothered to do," the candid star admits.

Ice-skating was, of course, "a huge part of it," Robbie tells Popsugar. "[I did] as much as we could possibly do before production started. I think I did about three or four months of skating, like five times a week for a couple of hours a day," she says, admitting that the training left her in awe of Harding's skating prowess. "Even if I had 10 years to practice, I could never do a triple axel," she says.