Zen means waking up to the present moment. That is, perceiving this moment exactly as it is, rather than through the filter of our ideas, opinions, etc.
One way to practice this is to ask yourself a Big Question, such as “What am I?” If you ask such a question strongly and sincerely, what appears is “Don’t Know.”
This don’t-know is before thinking. If you keep it moment to moment, then everything is clear. Then, each moment, whatever you’re doing, just do it.
When you’re sitting, just sit; when you’re eating, just eat.
According to Zen, existence is found in the silence of the mind (no-mind), beyond the chatter of our internal dialog. Existence, from the Zen perspective is something that is only happening spontaneously, and it is not just our thoughts. All of life that we perceive is constantly in a state of change. Every atom in the universe is somewhere different every millionth of a second.
via Zen Philosophy.