Asa Butterfield has joked that he is now a pro at push-ups, after doing plenty of them for his new film, Ender's Game.
The 16-year-old, who plays teen soldier Ender Wiggin in the big-screen adaptation of Orson Scott Card's sci-fi book, admitted he has done more push-ups during the shooting of the movie than he ever had before, after director Gavin Hood sent the young cast to bootcamp.
" Over the course of that film, over those four months, I'm pretty sure I've done more push-ups than I did in my life," he said.
"There was one scene where I had to do push-ups and in the space of those four hours, I think I've done more push-ups than I've done in five years prior to that."
Asa and his co-stars including Hailee Steinfeld and Moises Arias got trained up for their roles by enrolling into a boot camp.
"We had quite a few weeks before and during shooting that we learnt the things you would learn at military camp - marching, saluting, all of that stuff," he recalled.
"There were hundreds of us just marching and if one person messed up, everyone had to get on the floor and do 20 push-ups. It was hard work, but we had a lot of fun."
Despite the physical challenge, the actor enjoyed every minute of filming.
"We had such a blast. For me, every film I do, I gain something new and this was no exception. The amount of experiences I've had, the people I met and the things I got to do were so fun, they sort of made me who I am," he said. "As soon as I read the script, I knew this was something I wanted to do."
Ender's Game is in cinemas now.