Step One: Pick a victim. This should be a stranger who doesn't seem like he or she would be a fast runner.
Step Two: Take something from their person. Ideally, this is something both valuable and somewhat visible.
Step Three: Run away. Be careful not to run too quickly, as this could make potential pursuers give up. Similarly, running too slowly ends the chase. Keep this up until feeling exhausted, remorseful, or bored.