Today was my first seven mile workout. Looking forward to it, I knew that I did not want to be counting the minutes for over an hour. I shut my eyes and determined that I would not open them for at least 20 minutes. I needed to keep track of the time so that I could keep myself hydrated, which meant that I needed to look up within 30 minutes to make sure that I don't go more than the equivalent of three miles without a drink.
While my eyes were shut I tried to keep my mind occupied thinking about other things while internally keeping track of the time in 5 minute chunks. I determined that I would open my eyes once I thought it had been 25 minutes. Amazingly, when I opened my eyes it had been exactly 25 minutes (to the minute - not any more accurate than that). After drinking the allotted amount I logged a mental note that I had completed the first three miles in 26 minutes (my target is 27 minutes for three miles - I have done three miles in as little as 24 minutes).
When I shut my eyes again, I decided to mentally jog one of my normal three mile routes and see how accurate my time keeping was. At the mental end of the second three miles I looked at the clock to discover that it had taken 28 minutes - which is about normal for a second three mile set.
I spent the remaining minutes of my workout being amazed that the mind could so accurately keep time and remember in such detail the path that I had not run in weeks. What a marvelous gift a mind is.