Sometimes that brave spirit has been devestated to the point where "standing still" is all they can do. Maybe it could be more like a "broken spirit" and there is no energy left to be brave? I do think it would be more exciting as you said to "spend my energy braving the rapids in a kayak; much more fun and exciting than just tumbling end-over-end in terror, cold and wet, hoping I don't hit my head on a rock". But again maybe one can not swim. Or a person's loved one was killed in a kayak accident. It is not always the fear and terror of hitting one's head on a rock that would prevent a person to be brave or to continue exploring life. I do not think it is that simple. IMHO