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Not even a little bit of rain can stop Reese Witherspoon from working out! The Oscar winner braved the elements to head to a yoga class in Brentwood on Thursday morning. The petite star got her butt in gear before the class with a protein drink.

The mom-of-three wore a sporty black zip up and cropped leggings for her workout. Reese has been hitting Burn 60 in Brentwood on the reg for the past few months. We aren't sure if it's because she is exercising for a role in one of her upcoming films, or if she just got inspired after pics of her bum were splashed all over the Internet when photogs caught the Oscar winner accidentally flashing her backside in June. Maybe that's just what the star needed to kick her butt into shape!

For whatever reason she's on her health kick, we gotta hand it to Reese -- she really seems to be dedicated to working out! The actress has a couple projects in the works, so it's not surprising she's trying to stay in tip top shape for the big screen! The 37-year-old just wrapped Wild, a film based on Cheryl Strayed's 2012 memoir about her 1,100-mile solo hike. She's also set to begin shooting The Intern alongside Robert De Niro.

The 37-year-old made headlines earlier this year when she debuted her slimmer bod at the Devil's Knot premiere during the Toronto International Film Festival in September.

Devil's Knot, which hits theaters in 2014, is based on the true story of three teenagers who were falsely convicted of killing two 8-year-old boys in Tennessee. The trio, known as the West Memphis 3, were released two years ago after spending 18 years behind bars. Reese plays Pam Hobbs, the mother of victim Stevie Branch, and Colin Firth also stars in the movie as Ronald Lax, a private investigator who represented one of the accused teens.