The day before us is all we need to think about right now. We have enough responsibilities to attend to that we do not have to drag along the problems of yeterday, too. Nor do we have to be preoccupied with what will have to be done tomorrow.
You and I have a tendency to try to live the past, present, and future all at the same time. What we fail to realize is that we were never created to take on this kind of a load. The multiple thoughts, worries, anticipations, and concerns are simply much greater than we can bear. Still, we attempt the impossible, foolishly thinking we can do what only God can do.
God tells us to approach each day as it comes, as a gift form him. He even says we should not worry about what we will eat, for he will provide the food we need; his might is more than sufficient. Our entire attention needs to be centered on what is directly in front of us. We cannot afford to waste our energy by dwelling on yesterday's disappointments and tomorrows obligations.
Our whole being must be on being wholly available to God at this moment. He made this day for each one of us. Our most important concern should be to use these precious hours wisely for his glory.
Swaffield, Bruce C. Devotions for Life: New Ideas from Old Ways. Newcastle upon Tyne, UK: Cambridge Scholars, 2013 p. 224.