The expression “Living in the Moment” is a kind of Zen cliche, too easily bandied about without folks really knowing what it means. If you truly lived only “in the moment” with no thought of past or future you would stumble into walls or forget where you were going.
We can not only live in the present, but need to learn from the past and plan for the future … otherwise we would just keep repeating the same mistakes again and again, would not remember where we parked the car, and could not even go shopping for tomorrow’s supper or remember to get the baby out of the bath!
Human beings need to learn from the past, plan for the future. So, when Zen folks talk about “being in the moment”, a better meaning is that we learn to embrace this present moment, and our lives as they are now, without any thought that this moment should be some other way other than it is. We learn to drop excess thoughts and regrets about the past, and overly fixating on “what was” … even as we learn from the past. We learn to let the future be and take care of itself, and to drop excess worry about the future … even as we plan for a better future and take care of what needs taking care. We learn to “just be here” when we want to be … playing with our children, appreciating a mountain scene, at home or work … without always having our head lost somewhere else (though sometimes we must have our heads somewhere else and be occupied with thoughts of past and future).
That is “being in the moment”. This is what we learn from studying the great Zen and Buddhist teachers of the past, while living right this moment and preparing for tomorrow.