It seems to me that John's advice hits the mark for the layman, living in the world. Our vocation is to show Christ to those around us in each encounter we have with them. We show the Face of Christ by being His living icon: being the first to apologize, the first to offer forgiveness for wrongs, the first to show mercy, the first to respond to the needs of the poor around us. I believe that if I fail to show the Face of Christ to others I have failed twice: first, I have failed Him; second, I have failed my brother in the human family.
There is an exercise I have used that I call "the holy Face." I try to see Christ in the face of each person I encounter and try to discern what it is He wants and needs in that person in that moment; then try my best to fulfill it. Each such action and each such discernment is helped by the grace the Holy Spirit gives, so we are not only not alone, but also not totally on our own so that we can boast of being anything. Remember what the Lord has taught us to say. "When you have done all that you have done, say that I have done nothing except that which I, as Your servant, am first commanded to do. Have mercy on me."