Despite having been in the business for over 30 years and three Oscar nominations, Joaquin Phoenix still gets nervous every time he begins work on a new movie.

In the December issue of Esquire magazine, the 38-year-old spoke about his fears of acting.

"I don't know my craft! Every f**king movie, I feel like it's my first," he said, adding that he has been "uncontrollably shaking, physically nervous," on every film set.

Phoenix reportedly called making the 2010 film I'm Still Here the exception. Phoenix called it a pivotal moment in his life as it tracked his journey from his announcement that he was retiring from acting, through his transition into a career as a hip-hop artist.

Phoenix, the younger sibling of River (Stand By Me) and Rain (Hitch), also admitted he prefers to keep his life out of the Hollywood limelight.

"Here's what I worry about. When people are constantly adjusting your collar and your lapel and you just give in to it? It's over," he said. "You're no longer a human being...when you see an adult actor on set, they look infantilized. People are there to dress you. They bring you espressos and lattes and sh*t. it's like arrested development. We're all just little f**king runt kids."

Phoenix didn't say if this belief stems from the death of his older brother River at the young age of 23 back in 1993, when he was discovered dead outside Johnny Depp's Los Angeles club The Viper Room. It was later revealed he had died from an acute multiple drug intoxication involving lethal doses of cocaine and morphine.

Phoenix has had a successful acting career in Hollywood, starring in films including Hotel Rwanda, Gladiator, Walk the Line and The Master. He was nominated for Supporting Actor at the 2001 Oscars for Gladiator and was up for a Lead Actor award in 2005 and 2012 for Walk the Line and The Master respectively.  He can next be seen in Her, a comedy due out in January 2014.

His issue of Esquire hits newsstands Thursday Nov. 7.

Tags: Joaquin Phoenix Esquire Magazine