Are you counting the distance covered or the distance until you arrive?  There is a moment of inflection when we start counting the distance covered and then switch to counting down that which remains before we arrive at the finish.  It is my experience that once we believe we can reach the finish line (or the starting point is too far away to consider retreating) we start counting down.  If you run a marathon, somewhere along the course 19-miles run switches to 7.2 miles remaining.  We reverse engineer from our preferred destination all the time. The details change when we alter our orientation from the start or finish place.