When I run, I like to finish a particular distance, usually a round number, or I would look at the watch and time it just to end on 00, 05, 10 or similar increment of time.

Surely the exercise is equally valuable when it stops at 07, 13 or 21. Why was the 4 minute mile so significant, or the 2 hour marathon?

This not only happens in sports, but in other areas of life as well. The quest for round numbers can push us the extra distance to reach the round number, or stop us short of reaching our true potential.