What we need to do is teach ourselves to use the bigger muscles around the bottom of our lungs. When most people take a deep breath in, they can feel themselves grow a bit TALLER when what they should be feeling is they grow a bit WIDER.
A simple way to learn better breathing techniques and strengthen the primary breathing muscles is to sit or lay somewhere quite and relax. Place your hands at the bottom of your rib cage and take a deep breath in, concentrating on making your hands move apart as you breathe in and squeeze together when you breathe out. Do this a few times every day and you will soon find yourself reaping all the benefits of improved oxygen levels and those lovely relax hormones that are released when you are breathing correctly!