Because that blog was so popular, it’s clear that many people are interested in information about using abdominal breathing to help them reduce stress and anxiety, and it’s a good thing, because it works very well.
Many times people will try abdominal breathing and feel it’s either too hard, or they will judge themselves and believe they are doing it wrong. Usually, the reason it feels difficult or wrong is because stressful breathing has become habitual at that point and most likely has replaced natural and normal breathing patterns. You could say that the unnatural breathing has become the new normal, or at least what feels normal. Un-learning the bad form of breathing will feel unnatural at first, even difficult, but you can become better at it with practice.
It helps to understand that the diaphragm is a muscle that sits below the rib cage and when you flex your tummy, the tight muscles push the diaphragm upward and into the bottom of your lungs, thus crowding the lower part of the lungs. This pressure under your lungs leaves less room for air to enter, so you get less air and tend to breathe more into the upper chest, which is more like hyperventilating than really breathing in a relaxed way.
If you relax your tummy instead, and even let it pooch out a little when you breathe in, this lowers the diaphragm and allows the lower part of the lungs to relax downward and fill with more fresh air. This brings more oxygen into the body with every inhalation, and takes more toxic carbon dioxide out with each exhalation. For a while, you may have to consciously work at extending your tummy each time you breathe in, and consciously push your tummy inward each time you exhale, just until this starts to become more natural and the new normal.
Take it slow and be patient with yourself. Most of all, stop believing those false social norms that say you should suck or hold your gut in or try to flatten your stomach by holding your breath or flexing your stomach all the time. Those false beliefs only make you more tense and perpetuate even more unhealthy breathing.
Thanks to Robert Couse-Baker for the great photo - The Winds of Spring