Downey Jr: 'I'm a big old square'

Robert Downey Jr. has claimed that he didn't find it hard to play an establishment figure in Charlie Bartlett.

The actor, who has spent periods in jail and rehab, said that his wild lifestyle days are a thing of the past.

He told Screen Goblin: "It was easy. The truth is, lately anyway, I'm a big old square. I'm grounded and focused, and a little bit uptight.

"I'm a perfectionist. I live to be married, be a parent and do movies."

Downey Jr. recently claimed that playing a cocaine addict in 1987's Less Than Zero contributed to his drug problems later in his life.