You can retrain yourself in breathing to help your airways stay open longer as you breathe out. If you empty more of the old "stale" air out of your lungs, you will have more room for "fresh" air when you breathe in. This also takes less energy to get air in and out.
The diaphragm is the main muscle for breathing and is located between the chest and the abdomen. The diaphragm moves down as you breathe in, making the chest size larger so that air can flow into the lungs. When you breathe out the diaphragm moves upward and reduces the chest size so that the air is pushed out of the lungs.
Most people breathe using their diaphragm. Other people, because of certain lung diseases, such as asthma and COPD don't use their diaphragm to the fullest extent. Exercising the diaphragm can improve its function. Learning how is a part of re-teaching yourself to breathe.
While breathing in and out, keep the muscles in your chest and neck as relaxed as possible because using these muscles will increase tension and waste energy.
Pursed lip breathing creates back pressure on your airways and helps keep them open. This will allow more of the stale air in your lungs to get out and create room for fresh air to get in. You will be able to catch your breath faster and easier and will feel less short of breath.
The only way to retrain yourself to breathe is by practicing. Begin by going through the steps a few times an hour when you are relaxed. When you feel comfortable doing the exercises lying down, then begin practicing them while standing, walking, and sitting. You will find eventually these breathing exercises will decrease your episodes of shortness of breath. You will actually be able to do more activity.
Don't become discouraged and quit if breathing doesn't seem to be helping. Remember you are retraining your muscles and that takes time. The more you practice, the more natural and automatic it will become.
When you become tense or short of breath then slow down, concentrate, relax, and do your breathing retraining exercises. This will help you catch your breath.
Coordinate diaphragmatic and pursed lip breathing with your activity.
Exhale when you move from sitting to standing.