It is hard to be aware of what is really going on... The conscious mind is more fragmented than it wants to admit. Recently I attempted to exhale and prevent myself from breathing until I lost consciousness. But my mind subsequently made the decision to inhale, while still conscious, each time I repeated the experiment. The odd thing was that it felt exactly like I had made a conscious decision to inhale. It sort of made me realize that the conscious mind precomitting to not inhale and the conscious mind that really wants to breathe are two separate agents.