No wonder Kristen Stewart has such a hot body! The Twilight actress stays lean with regular yoga classes in West Hollywood.

We love how she goes in wearing jeans and a knotted shirt ... then emerges looking fresh-faced and ready to conquer the day.

Recent reports claim Robert Pattinson's ladylove has been spending extra time with her On the Road co-star Garrett Hedlund. K-Stew and Garrett allegedly partied into the wee hours of the night after attending the premiere for A Better Life last week. Ooh la la!

Aside from her intriguing love life, the 21-year-old hottie recently donated her used Keds to the website Shoe Revolt. Kristen's sneakers will go up for auction on August 1 with all proceeds benefitting the fight against sexual exploitation against kids.

Read about the ultimate goal involving the shoes ... after the jump.