If you're responding as a child would, and you're an adult, you are not in the moment. Being in the moment isn't psychobabble, it's central to being powerful, being appropriate, responsive, and thriving. When we act like freaked-out children, we're deep in the past, far from the moment, far from power, far from happiness. You can consciously hold your breath or accelerate it. But if you try to hold your breath too long, the subconscious takes over and forces you to breathe.
Breathing is a shared space.
I think the act of breathing is almost like a programming platform, an interface, a way to directly communicate between the conscious and subconscious. When I breathe deeply and consciously, my intellect sends a message to The Computer. In other words, I survived birth. By writing this I'm getting goosebumps. I see this as a confirmation, from my body to my mind that the message has been received at an even deeper level.