The former How I Met Your Mother actress stars alongside the action movie veteran in the Jack Reacher sequel in which she goes on the run with Reacher when she's framed for selling government secrets.

The role required a lot of fight and stunt training, skills Tom has acquired over the years, and competitive Cobie was so determined to be as fit and fast as Tom that she pushed her body to the limits, which was more of a challenge as she had recently recovered from a broken leg.

“There was so much running. I had broken my leg that summer and was only just off crutches a week before we started training so I was in the weakest possible shape of my adult life," she told U.K. host Graham Norton. "Tom is the fastest human being in films and so fast and I’m very competitive so wanted to at least keep pace."

Tom is well known for his running style in films and a compilation video of his movie runs has been made by fans. Since he is such a pro at running, he would push her to improve and he jokes she has graduated from "Tom Cruise School of Movie Running".

"Tom would give me a hard time if I didn’t keep up and didn’t run perfectly," the 34-year-old added.

She recently told ETOnline that they ran full speed in every location they filmed in, including one scene where they sprinted across a football field and most of it was cut out of the final movie.

"That (the running) was probably the hardest part of the training and physically the hardest part of shooting... It was one of those, 'I don't know how long my body is going to be able to do this,'" she admits.