Breath is automatic it happens to us throughout our whole life. Unlike something like our digestive system though we can consciously control the breath and this has an instant and positive impact on our nervous system. Firing up your rest and digest responses controlling your heart rate, speed of digestion and respiratory rate.
There is an intrinsic link between the breath and our emotions, if you are feeling anxious or stressed your breath is likely to be quick and shallow. Taking deep long expansive breaths deep into the belly, will make you feel relaxed and in control.
What is even more breathtaking is that regularly focussing on the breath and consciously controlling it through breathing exercises, will have a beneficial effect on the quality of your unconscious breath.
Breath is literally life. So take a deep breath.