Many of us can get into the habit of breathing only with our chest. This is far less efficient than diaphragmatic (belly) breathing.
Diaphragmatic breathing has loads more benefits as well:
Helps you relax and lower stress levels
Slows your rate of breathing
Can help to lower your heart rate and blood pressure
Helps improve improves your core muscle stability
How to Belly Breath:
Sit or lie flat in a comfortable position
Put one hand on your belly (just below your ribs) and the other hand on your chest
Take a deep breath in through your nose, and let your belly push your hand out
Breathe out through pursed lips as if you are whistling
Do this breathing 3 to 10 times
I hope you start to notice the benefits - it does take practice!