I've been beating in this concept about how crucial posture and breath really are. So I mention this in the context of practice. However, remember that we want to integrate the lessons into our daily lives.
One may ask, "Why do I need to be mindful of breathing when I already do it naturally?" This question has great merit. My response is that it's not really about the breathing, rather, it's about our state of being and the effects of breathing.
In Qigong we say that the body is a battlefield, the mind is the general, blood are the soldiers, and the breath is the strategy. Each of us need to know what our battle is about. Our wellbeing, health, and overall state of being can be effected by the things around us - only if we let them. This means that we have the power to not be effected as well.
Remember, breathing is your strategy to ward off the effects of stress, worry, anxiety or other negative energies trying to enter your space. Simply go to your center, remember this is your home and sanctuary where nothing can harm you. Whenever you find yourself in a stressful situation you actually can breathe through it. Take your mind to your abdomen. Bring your attention and intention here until the moment has past.