One of the most overlooked aspects of accurately shooting a bow is the necessity of controlling your breathing. The way to do this properly is to stop breathing for a short period of time, much the same as when rifle shooting, with slight modifications that take into account the different dynamics of drawing and shooting a compound bow.
When shooting a rifle, you normally take a rest, settle the crosshair on the target, take a deep breath, let half of it out, then squeeze the trigger. It’s mostly a passive effort physically. With a bow, you must physically exert yourself to draw the string back, then continue to exert yourself as you keep the bow drawn and the bow itself in an upright position. The other dynamic is that with a bow, the sight pins will be constantly in motion. Trying to keep them as steady as possible is physically taxing. Taken together, all these movements tend to deplete the oxygen contained in that held breath.
Therefore, you want to maximize the amount of oxygen in the bloodstream during the shot. When you see an animal coming into range and are getting ready to shoot, take a couple of very deep breaths and let them out slowly. Do the same when you raise the bow and draw it. This will help maximize the oxygen available to your muscles while helping to relax you as you go through your mental shot checklist. I personally try to take another deep breath as I settle the sight pin on the sweet spot. When the pin gets in the “zone,” I then slowly let out about a quarter of my breath, let the pin “float” on target, and squeeze the release trigger while concentrating on following through.
Most folks can hold their breath for about 10 seconds before the effects of oxygen depletion set in — and when that starts, your body will become shaky enough that an accurate shot is next to impossible. For myself, I find that the maximum time I can draw, aim and shoot accurately is right at that 10-second mark. For some archers it is a bit less than that, while for others it is a bit more. I personally try to draw and shoot in no more than five to seven seconds.
As you are practicing your shooting, try different procedures for controlling your breathing as you shoot. It might seem like a little thing, but in this case, it is a little thing that can make a big difference in your accuracy under the pressure of a hunting situation.