Katherine McNamara is no stranger to action-packed roles, from portraying badass characters like Clary Fray on Shadowhunters and Green Arrow on Arrow. But to play rookie Secret Service agent (and former Marine) Allison Miles, Katherine needed to look like a muscled military leader—on less than a month’s notice.

 Air Force One Down, which was digitally released on Feb. 9, tells the story of Allison’s first day on the job as a secret service agent—which, naturally, goes horribly wrong when the president’s jet is taken over by terrorists trying to derail a pivotal energy deal. Allison must use all her skills and training to protect the life of the president, played by Teen Wolf’s Ian Bohen.

In the short window before Katherine jetted off to Bulgaria for filming, she started weight training twice a day (once in the morning and another round in the evening) in between weapons and martial arts sessions. The actress also incorporated running and spin classes into her routine to keep her stamina up for packed days of shooting.