But the actor says he doesn't do it anymore

Tropic Thunder star Robert Downey Jr admits he was once obsessed with his penis.

The actor, who dated Sarah Jessica Parker for seven years, is now married to movie producer Susan Levin.

I was a compulsive, serial masturbator, he says. But it was the best thing I could have been.

I utilised that organ and rode it for everything it was worth.

Robert, 43, says he has now outgrown the habit, but claims most men are obsessed with sex.

Its no longer a motivating factor for me. My union with Susan is sacred, he tells The Sunday Times magazine.

Almost always, guys want to get laid. They have a girlfriend, they want to f*** her friend. But Im not that guy.

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Isobel Smith