That’s the milestone effect. That’s an exhausted runner who turns on her afterburners with one mile to go because she cannot bear to let the numbers on the stopwatch cross 4 hours. The milestones are completely arbitrary, of course: There is no defensible performance difference between 3:59:59 and 4:00:00. But of course, you understand the difference, and so do we. (One of your authors will sometimes walk laps around his bedroom at night in order to clinch 10,000 steps for the day. Absurd but true.) We all love milestones.
