I have always found runners and cyclists to be a strange lot. Why would they devote hours of their time to sweating except to get some kind of a rush similar to drug addicts?
This film shows that life clearly, as Johann (Andreas Lust) gets out of prison and, rather than seek a life of fame and glory as a long distance runner and settle down with a woman who loves him, he pursues a life of crime. He is seeking the same or a higher rush that he gets from running.
He doesn't quit running, but uses it to aid in stealing. It's never about money, as we never see him spend any. He just stores thousands of Euros under his bed. He even maintains a blank look as Erika (Franziska Weisz) tries to get some emotion out of him. His life is wrapped up in the rush he gets from stealing.
Both primary actors gave very good performances in a film that had you on the edge as time ran out for Johann.