Re: Breathing During Technique
this might seem a little facetious, but...
Breathe In - contract the diaphragm and intercostal muscles, increasing the size of the chest cavity. This causes a decrease in the pressure in the very thin layer of fluid between the rib cage and the lungs, which causes the lungs to expand. Lungs expanding causes a decrease in air pressure within the lungs, which causes air to rush from the higher pressure (outside the person) to the lower pressure (inside the person).
Breathe Out - reverse of the above.
The body has some very sophisticated mechanisms that respond to movement, carbon dioxide in the blood, and a whole lot of other things to regulate breathing - the trick is letting the body do its job.
"Naturally" as others have remarked