I was a HS math teacher too. When a student gets to "OH! I get it!", I think that they feel superior to themselves a minute ago, and to also to their buddy who doesn't get it yet, and those things are not really separable. And both feelings act as positive motivation, along with the intrinsic joy of understanding. You can ask them to indulge the later and ignore the former, but not with an expectation of success.

Some of my best students were motivated by their competitiveness with someone else in the class.