Rationality applied to swimming

The author was a lousy swimmer for a long time, but got respect because he put in so much effort. Eventually he became a swim coach, and he quickly noticed that the bad swimmers looked the way he did, and the good swimmers looked very different, so he started teaching the bad swimmers to look like the good swimmers, and began becoming a better swimmer himself.

Later, he got into the physics of good swimming. For example, it's more important to minimize drag than to put out more effort.

I'm posting this partly because it's always a pleasure to see rationality, partly because the most recent chapter of Methods of Rationality reminded me of it, and mostly because it's a fine example of clue acquisition.