Think of a time when you were really focussed on something that you wanted to accomplish and were enjoying being in that flow of accomplishment. You probably looked at the clock and were surprised at how much time had passed. Each brief moment is irreplaceable. So, our lives are becoming shorter at every moment and our time in this life is limited. By being completely in the present, we can live each moment fully.
Awareness is the key to being in the flow of time.
It means being conscious of the small details of what is going on and also the broader context. It includes keeping the past and the future in mind, while remaining focused completely in the present. This requires training the mind. By being aware of each breath or step we take, each movement, we stay in the present and feel the joy in being alive, instead of always looking forward to the fun we will have or back at what happened or might have been. By answering these questions and keeping them in mind at all times, you keep the horizon in view and something very interesting happens to your experience.