See Behind the Scenes of Reese Witherspoon's Trek in 'Wild'

Reese Witherspoon needed an adventure, and Cheryl Strayed’s book Wild provided the perfect map.

On Dec. 5, moviegoers will first get to see Witherspoon in the big screen version of Strayed’s incredible true story, starring as nature novice who hikes the Pacific Crest Trail all by her lonesome.

"She was at a place in her career where she wanted to just get out of her comfort zone and serve something so beautiful and powerful that she believed in," Jean-Marc Vallée, the film’s director, tells us in the exclusive featurette above.

Witherspoon won an Oscar for her portrayal of country singer June Carter Cash in Walk the Line in 2006, and in recent years had been looking for a role that could provide a similar challenge. In Wild, which she also produced, she found a whole lot more.

"It’s been so physically challenging, whether it’s climbing on the side of a mountain or crossing a freezing cold river and then falling into it," she says. "I had no idea it was going to be this hard."