Breathing during exercise is crucial to improving and growing. Breathing during a physical encounter is also essential. If your not breathing your dying is what was told to me by my sensei. Most people hold their breath when fighting or even when exerting themselves. This is bad very bad, as with exercise and self defense or fighting, there is a correct way to breath. One of the most simple things you can do to make your self breath during exertion be it self defense or otherwise is to speak, count or something. That forces your body to breathe. In the following referenced article by The Training Edge Magazine, they give the hows, whys, and some great facts about breathing. Read it, and do your best to learn and incorporate the strategies into your workouts and life.