Actor Seo In Guk confessed that the hardest moment in filming "No Breathing" was eating during scenes.

"No Breathing" is a movie about competitive swimming. Seo In Guk played Won Il, a boy who had to give up his dream of swimming professionally because of an incident. Because he played a professional swimmer, Seo In Guk had to learn to eat like a swimmer as well.

Seo In Guk said in the post screening interview, "Swimmers have incredible stamina, and to keep up that stamina they eat all day. I was stick skinny before we started filming, but once we started filming I gained weight very quickly."

Park Chul Min, who played Jae Suk in "No Breathing," also commented on Seo In Guk's eating scenes in the film, saying, "I have never seen anyone eat like that. Great actors can pretend to eat with anticipation and joy, but when a scene is filmed multiple times, they usually fake it and give up. Seo In Guk ate the same thing over and over again in a scene that had 20-30 retakes and ate it deliciously every time. I would've thought either he was crazy or was starved for weeks."

Seo In Guk quipped, "Yeah, I eat well. I was also hungry. I was also a bit crazy."

"No Breathing" is a movie about competitive swimming and it details the story of Won Il, swimming prodigy who stopped participating, and Woo Sang, a national swimmer and Won Il's rival, as they begin to attend the same high school. The movie also features Yuri from Girl's Generation.