math happiness or proficiency?

In a study done on math students around the globe, and their levels of happiness compared with how proficient they actually are in math, some interesting results have appeared. It appears there is an inverse effect.

Enjoying math more means you stink at math.

Hating math means you are good at math.

Here's the article:math article

This theory makes alot of sense. So as a math teacher, what should be the priority? Happiness or Proficiency?

I at least think you can foster an enjoyable learning environment for math where math is still challenging, and the students are being pushed. Then they can still be good at it, but maybe enjoy the time they spent learning math, maybe not math itself.