Mark Ruffalo didn't need much help getting into character as The Hulk in The Avengers.

The actor, 44, looked to his son Keen for inspiration. "I was channeling my 10-year-old son, who I dedicate my performance to," Ruffalo told Access Hollywood at the film's premiere in Hollywood Wednesday. "It's that horrible moment in a child's life when the world expects a certain kind of behavior from them, but they can't quite hold it together and they break out in rage and it's Hulk-like."

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Ruffalo added: "I used him quite a bit for that character." (The actor and his wife Sunrise Coigney, 39, are also parents to daughters Bella, 6, and Odette, 4.)

VIDEO: See Mark Ruffalo morph into Hulk in The Avengers trailer

Unlike his costars Robert Downey Jr., Chris Evans, Scarlett Johansson, Jeremy Renner, Samuel L. Jackson and Chris Hemsworth, Ruffalo won't be wearing a super hero costume on the big screen. Instead, he donned an "incredibly unflattering" motion capture suit to portray the larger-than-life Marvel Comics character.

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"I was wearing a frumpy little, like, linen thrift store suit and they were all in their super hero costumes looking very, very full," Ruffalo told Access Hollywood. "But I think it was exactly how Bruce Banner feels -- a little out of place."

The motion capture suit left little to the imagination, Ruffalo added. "It was showing everything and not showing enough -- if you know what I mean!"

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