As far as I understand, in Zen-influenced "mindfulness," it is to keep "nothing/無" in your mind to avoid distraction and simply focus on the breathing. That is "quiet/ 静" mindfulness.
In Buddhist/ Asian philosophy, many things are paired with the opposites, i.e. Ying陰-Yang陽, just like a coin has 2 sides (but it is still the same coin). So, my question is how about keeping "mindfulness" with "movements/ 動"? And wonder if "movements" could be either athletics and/or musical activities (and I am sure there are many more possibilities)?