One way I control my breathing (get it back in control) is to whistle. When I'm alone, I sing. Singing is more annoying than whistling, I think, and I can whistle almost inaudibly. I started doing it when I practiced my ukulele and I couldn't keep up with the breathing of the song (that was a few years ago, when I wasn't as fit). I started it unconsciously, and I noticed last year that I was doing it on hills unconsciously. Now I use it as a tool consciously on the arc-trainer at the gym, while running, riding, or playing uke (which I hardly ever do anymore).

Karen