We were born into it. Feeding time, bed time, feeding time again. Later, play time was added, then school time, then work time. Life seems to be on a schedule, one day and then another.
God has set order into place. He tells us in Genesis 8:22 that, "As long as the earth endures, seedtime and harvest, cold and heat, summer and winter, day and night will never cease." He has fixed the routine by which we live, reminding us that our very existance is in His control.