It is as simple as this.
In the doing, in the chaos of everyday, be aware that you witness the very soul of the other in their deeds and their words. Be aware of the moment. The other is here now, for a brief time, like thyself, never to be again, a flower that blooms and withers and dies so quickly, in the blink of the eye of the Buddha. You, even your humble self, are witness, and perhaps your entire purpose is to be so. We are all witnesses of each other. For that is the way that the world was made. We are witnesses to each other and to the whole world as it is.