For all his running, never once is Cera chasing anybody. (The closest he comes is in Juno: just after crossing the finish line and failing to locate Juno in the stands, he runs to the hospital where Juno is giving birth.) He is never the pursuer. But then again, he is rarely the pursued. In Nick and Norah, nobody chases after him when he runs away, and in Youth in Revolt he is pursued only by a phantom, an id he cannot vanquish and is not sure he wants to. That is the essence of his running: a contest with himself, a test to see if he can become a man — if he can, to use the term of art, man up.
Have you ever noticed that in all of his roles, Michael Cera ends up running? Here’s a great piece from the Believer in which the particular brand of nerd Cera tends to play is tied into the act of running. It’s worth reading!