Writer-director Tony Gilroy said he cast Renner because he's an amazing actor who can handle the physical demands of the film.
Renner said he enjoyed being pushed to his limits.
"If it was easy, I knew how to do it, then, you know, how boring would that be? I like the challenge, I like to overcome the obstacles and see if I can't surprise myself and give the director more than he ever anticipated," Renner said.
While "The Bourne Legacy" is filled with action, Renner says there was one scene that almost did him in.
"We did it 25 times, I think we ended up using take 2, so, I thought I could do it better, I guess I didn't," he said with a laugh.
Renner has been a working actor for the past 10 years, but his profile increased after earning Oscar nominations for "The Hurt Locker" in 2008, and then "The Town" in 2009.
He then jumped to big budget hits, including "Mission: Impossible - Ghost Protocol" in 2010, and then, earlier this summer, he was part of the team in this year's biggest hit, "The Avengers."
His profile may have gotten bigger, but his ego hasn't.
"The only time I sort of realize it, things around me have changed, is trying to go pick out some tomatoes at the grocery store," he said. "I just got to shop later in the evening, like midnight or something."
"The Bourne Legacy" is in theaters Friday. In January, Renner stars in the "Hansel and Gretel: Witch Hunters."