Actress Lynn Collins struggled to hold back while filming fight scenes for new Disney epic John Carter because her childhood karate training made it a "real challenge" not to "hurt people".
The X-Men Origins: Wolverine star's parents were keen martial artists and they regularly enrolled the young Collins into fight training classes in Japan while she was growing up.
She was able to draw on her karate skills for her role as Dejah Thoris, the Princess of Helium, in the upcoming sci-fi adventure - but the actress admits her years of karate became more of a burden then a blessing on set.
She tells WENN, "I spent my summers in Japan where my parents were getting their fourth and fifth and sixth don in Shito Ryu, which is an Okinawan style of karate...
"Karate fizzled out because of acting and this is the first time that the two have married and it was really emotional for me at the beginning. It was hard to bring back the memories from my childhood; it was a childlike feeling that I had to turn into a forceful, feminine and adult (feeling) and to not hurt people was a real challenge. It's completely a part of me now."
Collins stars alongside Willem Dafoe, Thomas Haden Church, Bryan Cranston and Taylor Kitsch as the title character, a former American Civil War captain who is transported to Mars.