What zazen causes in you is what you have and how you are, not something which is different from your actual existence. Every one of us has some deep concern about ourselves -- to be a very valuable being for everything, for yourself and for those to whom you concern. You want to be a truly important being for all. It seems that meditation practice gives some way to clarify your being as the important being, the seeker of deep understanding, where you exist, what actually is going on and how you can be, how you can exist.
Somewhat naturally to come to sit without knowing what this action is has some unclear ambition in it; that means a very natural unaware confidence in your being. To see people, including myself, sit on the cushion, this is very ambitious basically. To desire perfect enlightenment is the biggest ambition you can have. As far as you sit, you have to have such ambition. To understand other existences also is very ambitious.
How do you experience the existence of others? It is very difficult to really know that others exist, are a different existence from yourself. Usually what you see is who you are, so what you experience is when and where you existed. Actually we don't care whether others exist or not, but when you reach to ultimate understanding of yourself, a big question appears. Is this just me existing, or are there some other people on this earth? Model and primitive experience is child's consciousness, two to three years old. They don't have a sense of past and future, only the present, and the only existence is themselves. Even though we become a member of society and see and are taught that there are other existences, that stays with us as knowledge. Turning point is to begin loving other people. Do you remember when you began to love beings when you were very small? It was a very big event. It's a kind of opening up of other worlds with your capacity and opening yourself at the same time, opening up to accept other existences.
Very difficult person to meet with and understand is actually our own self. The whole experience to get to know others is actually to have a standard to reach to yourself. Endlessly approaching to the matter of oneself, this is the focus of zazen practice. Clarifying your own existence is actually expanding your own self endlessly. Whatever you experience becomes yourself, and you see into yourself with others' existence which is not different from yourself.