Breathe in deeply through the nostrils: first into the bottom of the lungs, letting your abdomen expand to its fullest extent; open your rib cage like a fan, and lift your chest last of all, without raising the shoulders. You will be amazed to find how much air your lungs can really take in.
Now try holding your breath for a few seconds (anything from 3 to 60 seconds). This may make you dizzy at first. Don’t worry, it only means that you are unused to taking in so much air.
Now breathe out. Do so completely, making the sound huh (silent hs) at the end to squeeze out the last particle of used air and making room for fresh air. Exhalation (breathing out) is every bit important as inhalation (breathing in). If you are not used to using your lungs, you might find your lungs, ribs and chest aching at first.
Whether you breathe out through the nostrils or mouth isn't too important. Nostrils would be good, but mouth is ok if you are more comfortable that way. And it will probably easier for you to end with the huh.
Breathing is fundamental to good health, yet many people seem to forget its importance. Fortunately it doesn't take long to return to good habits. If you feel you need a bit of space in your life to relearn, book an appointment at The Breathing Clinic. You can book a 40 minute session at http://www.carolinebrowntherapy.com.