Let us look at some more detailed aspects of Pranayama. I start the whole process by exhaling and when I exhale what is in fact happening is that I feel the breath going down. The rib cage, which has been expanded in the inhalation, in the exhalation is going back. The diaphragm is going up to expel the air and the abdomen is contracting.
In order to make the exhalation complete, one has to feel that downward movement fully. Where the awareness has come, this is where we are connected with the movement of our breath. So when the awareness has come down, what we feel as a downward movement, from that point the inhalation starts.