Today in kids class we played the following game: do as many laps of bear walk in 40 seconds as you can. We played it 5 separate times (with lots of rest in between every time). The goal (each successive time) was to improve on your highest score.
Not everyone got a new high score each time but everyone improved on their original score at least once. Pretty amazing, considering how hard the students went for it the first time. My suspicion is that part of the improvement comes from familiarity – doing the same thing the second or fifth time is easier because you know what is coming but I also suspect that some of the improvement comes from the urge to beat your own old score. It feels good to improve. It feels good to have a measurable number and say “last time I did 2 laps of bear walk. This time I did 2 and a half.”