Summarize the following:
The diaphragm is a muscle that sits like an upside-down bowl just beneath your ribs, contracting and relaxing to move air through your lungs. Deep "belly breathing" that visibly moves your abdomen in and out helps strengthen this muscle and improve your endurance. If your belly stays flat and your chest pumps up and down, you're taking shallow "chest breaths," and will fatigue sooner. This will help ensure that you are getting enough oxygen to your body, and is the best way to prevent muscle and lung fatigue.  It also helps increase endurance by getting proper oxygen circulation to your muscles. Your mouth is wider than your nostrils, allowing you to take deeper breaths of air. Allow air to enter through both your mouth and your nose. Most experienced runners coordinate their breath with their steps, such as the popular "inhale for three steps, exhale for two" (or simply "3–2"). This helps you breathe more consistently. You may also be forced to switch to a different pattern (such as "2–1") at higher speeds, which helps you keep track of the intensity of your run. There are several popular alternatives to these patterns, such as "2-2" or "2-3." Experiment with different breathing patterns to find the right one for you. You should be able to form full sentences while running without huffing and puffing.

Summary:
Breathe with your diaphragm. Take longer breaths. Keep your mouth open. Find a breathing pattern. Use the "talk test" to determine if you are breathing enough.