Joaquin Phoenix has admitted that the strain of performing in I'm Still Here made him want to leave the project.

The film follows actor as he supposedly retires from Hollywood to pursue a hip-hop career. He had to stay in role at all times, even for his controversial appearance on the David Letterman show.

Both Phoenix and Casey Affleck, who made his directorial debut with the movie, continued to claim that the actor's behaviour was not a performance until shortly after the movie's US release.

Phoenix told Extra: "At some point, it became such a public spectacle. To be frank, we were kind of hostage to the process. There were times, honestly, where I wanted out. Even on a conventional film, I'm done after four months. But this went on and on."

However, despite the pressure of maintaining his public performance, Phoenix insisted: "I wanted to make a movie with my friends and make one in a different way. I wanted to have a different experience, and I'm really happy to have done that."

Speaking of the moment when filming began, Phoenix said: "'Is this, like, the moment? Shall I announce my retirement right now?' And Casey said, 'Yes'. It wasn't planned."

The 35-year-old actor added that his infamous appearance on Late Night with David Letterman was never intended to embarrass the TV host. "I wasn't on the show to make a fool of him," Phoenix explained.

"In this film, I think the only person who comes off as a real jerk is me."

Source: Press Release