You can breathe deeper or shallower to control that. Maybe that's the point. Because you have to follow a certain timing, your body is not on autopilot anymore

You can breathe deeper or shallower to control that. Maybe that's the point. Because you have to follow a certain timing, your body is not on autopilot anymore, so you have to be conscious of your oxygen needs, maybe even adjust them (for example, by calming down).