I had to do that when playing music. Musicians tend to concentrate on playing so much that they get the most awful peculiar facial expressions going. Performers learn to retrain this. I retrained my face to stop scowling and look relaxed and happy too when I play.
But oddly, when I'm biking I always catch myself naturally smiling even when there is no real reason. Biking does that for me.![]()
Runners, on the other hand, ALWAYS seem to look like they are miserable.![]()