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Reese Witherspoon can feel the burn and is loving it! The Oscar winner was all smiles after her workout at Burn 60 on Tuesday morning in Brentwood, Calif. Looks like those endorphins have definitely kicked in!

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 is currently filming 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 mom of three 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 gear!

The 37-year-old made headlines 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.