Jake Gyllenhaal was back to his fitness routine in LA yesterday. His four-legged running partner Atticus skipped this jog, but Jake looked great all on his own. The actor is prepping for a busy month as he begins promoting his next film, Source Code. The futuristic thriller is out April 1 and first up he'll be bringing it to premiere at South by Southwest. He may also be perfecting his physique for a couple exciting new roles. He's rumored to be starring in the cop drama End of Watch and is one of the front-runners who could take over for Matt Damon in the Bourne franchise.