It is Easier to Focus on Breathing
Your mind looks for something to distract itself with. Many find that if they forego running with music, they are presented with the opportunity to concentrate on the rhythm of their inhales and exhales while in motion. Some runners fall in love with this aspect because it keeps them in touch with their stamina and body during the whole running process, and at times even allows them to find breathing methods that help them improve their distance and time.
Another thing to note: Many people who listen to music tend to push themselves according to the beat, which can cause them to breathe irregularly, especially if they like fast beats. When your breathing is heavy and fast, it is your body’s way of telling you that it is becoming fatigued. If you can match your pace to your breath, you may find that you can improve your physical endurance and run further distances.