Before the hourglass, as long ago as 1600 BC water clocks were used in Egypt and Babylon. Ancient Greeks called theirs, clepsydra - the water thief.
By the middle ages, the hourglass became more usefull for keeping track of time, especially on boats where the hourglass wouldn't be affected by the rocking of the boat on the sea like the clepsydra would.
Perhaps we ought to visualise time as a precious commodity. Since the runaway success of mechanical timekeeping, we are almost conditioned to see time in a circular fashion, but perhaps this is misleading - after all, and as we know, time does march.
Set a start and end time and you will see the sand of the hourglass falling in real-time, proportional to time remaining.
Shorter intervals will be reflected in a faster movement. If the time interval is longer than 15 minutes, you may not easily detect the movement - but it is happening, come back and check whenever you like.
Monitor visually how much time is actually left to finish your project. Put an end to procrastination.
