The actress shared the shot today from the set of the film adaptation of Cheryl Strayed's adventure memoir, Wild. Strayed shared the same photo.
Wild, which came out in March 2012 and is ranked No. 126 on USA TODAY's Best-Selling Book list, got a huge boost when Oprah picked it for her new 2.0 Book Club.
Strayed's book chronicles her decision to hike 1,100 miles along the Pacific Crest Trail after her mother died and her marriage fell apart. The movie will be released next year.
Witherspoon, 37, has been sharing photos of the process, including one in which she's getting "fake feet" made and another showing the Oregon horizon at sunset. But this is the first one of her in character.
Deadline reports that Laura Dern, 46, has joined the cast as Witherspoon's mother.
And for comparison, here is the real Cheryl Strayed