Belly breathing can assists with control of breathing pattern by the use of the diaphragm to improve ventilation, oxygenation and excursion of the diaphragm.
Position: lying down (sitting when you become more advanced in this technique) Place one hand on belly and other hand on chest bone (sternum), feel what is happening this is your gauge for noting improvement as you breath normally then with diaphragm intent. Notice the difference. Inhale through your nose, fill your lungs slowly and completely without expanding the upper lung cavities too much, this means that your chest hand will move very minimally or not at all, the latter is what we want to achieve. Then…The Belly hand will feel the most movement as the depth of the inhale increases.
Your inhale will naturally give you a big “Buddha Belly” as this is the goal, pay attention to your body and avoid distending your belly with force.
On the exhale; through a neutrally opened mouth, allow the air to expel like a slow leak in a tire. Repeat the process initially for 5 minutes then when you feel, not think, you are ready for more increase the time by 1 min/day, do this twice a day to start for first week, then second week progress to 3 times. Always listen to your body. You may need to take baby steps to get here, there is no race, and progression is your friend.