I'd say the zone is something that just happens. You can't force it and you can't make it happen. It just does. It is your reward for all the hard work and time spent on the water. It is almost and out of body type experience...like you can predict what is going to happen next. When I am in my "zone" I don't necessarily think of it as intense concentration. It is more like a calm relaxed and confident feeling. I just know i am going to make that 80 foot cast between the trees, off the bluff face, under the rootwad and land a fish.