Hi Adam,
Running is an intense exercise it requires more oxygen for a good performance and also proper breathing allows more oxygen to enter into lungs and muscles.We need to do cadence breathing, 3-4 steps inhale,then next 3-4 steps exhale.Avoid protracting of shoulders while running,expand your chest and shoulders to increase the air entry into lungs.Start slow by doing just a brisk walk or low intensity mild exercises and gradually increase your pace. This type of breathing will help increases lung capacity and keep your breathe smooth while running.