How breathing is supposed to work:
- The abdominal muscles relax while your diaphragm contracts downward, pushing all your guts out of the way.
- Your intercostal muscles contract to expand your rib cage, lowering the air pressure in your lungs and creating a vacuum in the chest cavity.
- Air flows through your nose and mouth in response to the vacuum.
- The intercostal muscles and diaphragm relax while the abdominal muscles contract, pushing air out of the lungs.
"Now, if you're hunched over your desk for hours, what happens? The amount of oxygen you receive thus is less than optimal. In fact, a 2006 study from the American Academy of Physical Medicine and Rehabilitation showed that crappy posture produced the worst lung capacity and expiratory flow compared to normal sitting and a posture designed to mimic standing spinal alignment. Rene Cailliet, former director of the department of physical medicine and rehabilitation at the University of Southern California, asserts that the reduction in lung capacity can be as much as 30 percent."
If you're not used to breathing properly anymore, you have to retrain yourself what it feels like. Here's a good, basic diaphragmatic breathing exercise, as described by the University of Georgia, that I used as a vocal major and teach to my music students. You should start by doing this exercise 5 to 10 minutes at a time 3 to 4 times a day:
And while you are here, visit https://samim.io/breath/ and just breath for a moment.