Well, okay, here's my stand on this. If you're going to survive in a Zombie Apocolypse, you can't be the fat guy who sits in his basement and plays WoW all day. (Probably not, anyway. Maybe you'll fight them off with that golden Lord of The Rings dagger. Who knows.)
But really, the fact that she WAS able to do those things, explains COMPLETELY why she was there, and why she was surviving easily. If you're a cripple, I don't expect you to be alive in this world. I think Molly is actually far more believable, due to the fact that she proves she knows how to survive. Someone like Omid or Christa? How are they doing it? I don't really understand.
Overall, Molly being a badass is why she's alive. So, yeah.
no but really though kenny is alive i swear