I have always been a naturally shallow breather, but only realized it about 10 years ago. Honestly, not knowing something so critical about oneself can be a bit disconcerting initially. Once I realized that my excessive yawning and low energy levels were due to shallow breathing and being a bit overweight, I started to develop different BREATH WORK exercises and noticed remarkable and progressive results.
Breath work is a conscious form of working your breath to bypass the mind and enter a different state of energy awareness. This practice gives your brain the executive function over how much oxygen/energy your body is processing. At first, I simply consciously increased my oxygen intake while slowing my breathing down to help relax myself. I would do this whenever I caught myself yawning or even snorting. Initially, I was overweight which caused sleep apnea and disrupted my breathing quite frequently. Quickly noticing how much better I felt doing these exercises, I began to experiment with advanced techniques. Adding some visual aids for intention. I found that I could even manifest some goals by focusing on images while doing the breath work. Sacred geometry like Metatron's Cube, Sri Yantra, and the Flower of Life were all effective with this technique. I continued to increase this type of activity and noticed how much better I was sleeping and a general elevated wellness.
Then I began to institute BREATH WORK into situations where physical concentration was needed like sports. Specifically, tennis is a great sport for instituting breath work exercises. There is a break before each point where I increase my intake breath flow. It may sound funny to those around me, but it helps me focus on that little yellow ball. This enables me to pick that ball up just a split second faster while increasing the oxygen flow that my body is currently processing at an accelerated pace due to the physical exertion. Especially later in that 3rd set when we all tend to gasp a little harder.
There are generally no hard rules when it comes to establishing your own breath work routine. It is different for different people in different situations and contingent upon what your goals are for it and how you personally react to it. Have some fun with it. Experiment with it a bit and see what works best for you.