There's a guy called the Penguin that writes for Runners' World. He likes to say that he waddles around. To him (and I agree) being a runner is a state of mind:
http://www.runnersworld.com/article/...2126-0,00.html

In short, being a runner means taking this more than casually. You don't just go out there and flaunt your cute running clothes on the boardwalk. You're actually doing it with a purpose. I think that about summarizes it.