Everyone has mucus.  It is one of the many defense mechanisms in our body’s arsenal that protect us against infection and other un-pleasantries. In fact, if Lady Macbeth were a chest physiotherapist, she may well have been known for another quote: “Out, damned snot!”  Before we discuss how to minimize and mobilize the secretions (mucus) that may accumulate in your airways as a result of your disease, it will be helpful for you to have a basic knowledge of what mucus actually is and what mucus actually does.