I run too. I try to keep it to a bare few days a week, for fear of compromising my yoga practice. But it's in me, that need to just get out there are run my brains out. My practice has illuminated my running, clued me in to the way that I can moderate and modulate around the breath, pace myself to pull through to the end. My body aligns more naturally than it used to. His body has figured all of this out after years, without too much analysis. His really is a habit of, "one percent theory, 99 percent practice." After a while, these things simply go without saying. Right foot, left foot... that's all there really is to it.
My dad has a book on his shelf called "The Loneliness of the Long Distance Runner." That's it in a nutshell, isn't it? Ashtanga yoga, and running. Ultimately, solitary practices. You might "share your breath" if you practice in a Mysore room. But you are really alone on your mat. Maybe this is why they both suit me so well, I'm comfortable here, alone in this space.