The following is an excerpt taken from Eckhart Tolle's book The Power of Now - A Guide to Spiritual Enlightenment which discusses the difference between psychological time and clock time and how our identity with psychological time inhibits our being able to live in the Power of Now.
"Learn to use time in the practical aspects of your life - we may call this "clock time" - but immediately return to present-moment awareness when those practical matters have been dealt with. In this way, there will be no buildup of "psychological time," which is identification with the past and continuous compulsive projection into the future.
Clock time is not just making an appointment or planning a trip. It includes learning from the past so that we don't repeat the same mistakes over and over. Setting goals and working toward them. Predicting the future by means of patterns and laws, physical, mathematical and so on, learned from the past and taking appropriate action on the basis of our predictions.
But even here, within the sphere of practical living, where we cannot do without reference to past and future, the present moment remains the essential factor. Any lesson from the past becomes relevant and is applied now. Any planning as well as working toward achieving a particular goal is done now.
The enlightened person's main focus of attention is always the Now, but they are still peripherally aware of time. In other words, they continue to use clock time but are free of psychological time.
Be alert as you practice this so that you do not unwittingly transform clock time into psychological time. For example, if you made a mistake in the past and learn from it now, you are using clock time. On the other hand, if you dwell on it mentally, and self-criticism, remorse, or guilt come up, then you are making the mistake into "me" and "mine": You make it part of your sense of self, and it has become psychological time, which is always linked to a false sense of identity. Nonforgiveness necessarily implies a heavy burden of psychological time.
If you set yourself a goal and work toward it, you are using clock time. You are aware of where you want to go, but you honor and give your fullest attention to the step that you are taking at this moment. If you then become excessively focused on the goal, perhaps because you are seeking happiness, fulfillment, or a more complete sense of self in it, the Now is no longer honored.
It becomes reduced to a mere stepping stone to the future, with no intrinsic value. Clock time then turns into psychological time. Your life's journey is no longer an adventure, just an obsessive need to arrive, to attain, to "make it." You no longer see or smell the flowers by the wayside either, nor are you aware of the beauty and the miracle of life that unfolds all around you when you are present in the Now. "
To discover how you can use The Power of Now to overcome many of the daily struggles faced by mentally living in the past and in the future instead of Now (the present), click to learn more The Power of Now: A Guide to Spiritual Enlightenment.