Ben Foster confessed that he took performance enhancing drugs so he can perfectly portray Lance Armstrong's character in 'The Program.'

Foster was so serious in portraying the character of the famous cyclist that he ended up doping himself while filming.

"Doping is not the reason why Lance Armstrong won but it did shape a culture at the time, and it certainly shaped him, and I wanted to understand - on a personal level, on a cellular level - what that experience is like," Foster said during an interview at The Toronto International Film Festival.

Though he decided to gamble his health, he said that he took the risk, under the supervision of a nutritionist and a wellness doctor. He also admitted that coming off the drugs- which he didn't specify, is the most difficult part. "That's where your health concerns will come in. And it took a while for me to right myself. But that was a calculated risk and part of the joy of the job, I suppose," he said.

Apparently, his fellow actors, movie director and the whole production team didn't know that he was doping himself while filming the scenes.

"It hadn't struck me that he would, but of course that makes perfect sense," Chris O'Dowd explained during the interview.

Director Stephen Frears said, he had not idea that Foster got himself involved with such danger while they were filming but reckoned that there is nothing he can do about it and he can't turn back the time. However, he praised the actor for his astounding talent.

"The truth is, he's so good in the film, and I'm so grateful to him for being that good." Frears said.  

The controversial cyclist, Armstrong, once a famous athlete that has seven Tour de France titles, was stripped of his titles and totally banned from cycling after admitting on the Oprah Winfrey Show back in 2013 that he did use dangerous drugs.