It implies to use your mind to regulate breathing and direct qi flow in the body.  However, it doesn't mean that you put emphasis on exerting your mind to guide qi to a definite direction, when you feel qi flow in the body.  Never deliberately bulge your belly, or throw out chest, or purposely make abdominal breathing improperly, or force "gentle, fine, even and long" breathing.  Let matters slide, with natural appearance of the "gentle, fine, even and long" breathing.  The feeling like cold, warm or water flowing experienced during qigong exercises is known as the qigong sensation.  Do not pursue such sensation on purpose or exaggerate it.