Diaphragmatic breathing
Diaphragmatic breathing is a technique where you consciously recruit your diaphragm, in order to efficiently fill your lungs. Put one hand on your chest and one on your tummy and breathe into the tummy rather than the chest, as this means that your domed diaphragm is pulling down for your lungs to fill.
What they say
The diaphragm is a large, dome-shaped muscle located at the base of the lungs. Diaphragmatic breathing is meant to help you use the diaphragm correctly while breathing. This breathing technique offers several benefits to your body including reducing your blood pressure and heart rate and improving relaxation. (Source: Cleveland Clinic)