The main causes of illness is taking in toxins through processed foods which deplete some nutrients from the body but the worst thing they do is build up in organs and other body parts to form tumors which destroy tissue and could spread as parasitic material to kill you. These poisonous cells in the tumors live off the healthy tissue thereby killing it.
There are toxins everywhere like all the wireless waves around, air polluted by carbon monoxide from cars, chlorine in the water you wash your body with, the freon in refrigerators, chemical cleaning solutions on carpets, etc.
The body tries to clean itself by getting rid of toxins in the form of extra mucus, fever nausea, diarrhea, headaches, cold or flu symptoms, sneezing, etc.
Waste matter is excreted from the rectum through stools, from the bladder through urine, from the lungs through breath, from the pores of the skin through sweat. If there is something wrong with your expulsion system like if you’re constipated, waste stays in your body.