Believe it or not, most individuals don't know "how to breathe"! In the human performance world there is a concept known as Diaphragmic Breathing (aka-Belly Breathing) where you teach yourself how to breathe through your belly verses your chest. When you breathe through your chest, you only inhale about 20-25% of your lung capacity, where when you breathe through your belly, you will can literally inflate your entire lung capacity.
Here a a few ways you can "teach yourself" how to breathe:
1. Lay flat on your back and put one hand on your belly button, one on your chest. Focus on filling up your belly with air prior to allowing the air to fill up into your lungs (i.e. your chest). It is tougher than it sounds. You will realize that you are wired to breathe ineffeciently.
2. After you become more effecient and filling your belly first, then focus on completely exhaling all of the air in your lungs. By gently pressing on your chest when you exhale, you will notice that you don't get rid of the old air completely, this doesn't allow room for fresh air full of oxygen to feed your working muscles.
Here is a video that I shot that illustrates the drill: http://www.youtube.com/watch?v=VMNo2oois94
There are a few advanced drills that you can do, but for right now give that a try and let me know how it goes for you. Once you have these drills mastered, I will be happy to provide you the advanced drills.