Before you determine to do it, you have difficulty, but once you start to do it, you have none. Your effort appeases your inmost desire. There is no other way to attain calmness. Calmness of mind does not mean you should stop your activity. Real calmness should be found in activity itself. We say, "It is easy to have calmness in inactivity, it is hard to have calmness in activity," but calmness in activity is true calmness.
When we sit in the cross-legged posture, we resume our fundamental activity of creation. There are perhaps three kinds of creation. The first is to be aware of ourselves after we finish zazen. When we sit we are nothing, we do not even realize what we are; we just sit. But when we stand up, we are there! That is the first step in creation. When you are there, everything else is there; everything is created all at once. When we emerge from nothing, when everything emerges from nothing, we see it all as a fresh new creation. This is non-attachment. The second kind of creation is when you act, or produce or prepare something like food or tea. The third kind is to create something within yourself, such as education, or culture, or some system for our society. So there are three kinds of creation. But if you forget the first, the most important one, the other two will be like children who have lost their parents; their creation will mean nothing. Usually everyone forgets about zazen. Everyone forgets about God. They work very hard at the second and third kinds of creation, but God does not help the activity. That is why we have so many problems in this world. When we forget the fundamental source of our creating, we are like children who do not know what to do when they lose their parents. If we are aware that what we do or what we create is really the gift of the "big I," then we will not be attached to it, and we will not reate problems for ourselves or for others. So to do something through and through is to resume our true activity of creation. This is why we sit. If we do not forget this point, everything will be carried on beautifully. But once we forget this point, the world will be filled with confusion.
from the section "God Giving", in Zen Mind, Beginner's Mind