Illness simply refers to the lack of good health. The presence of a disease is also considered to be illness. Health is the state of social, physical and mental well-being. When a person is not fit when it comes to all these fronts, he or she is considered to be “ill” and suffering from an illness. Illness is not just the presence of disease or any infirmity. Conditions of the body and mind that cause pain, improper functioning or distress to the person or to those who are in contact with him can be considered as illness.
In the words of Jonathan Davis, “A lot of people don't realize that depression is an illness. I don't wish it on anyone, but if they would know how it feels, I swear they would think twice before they just shrug it.” Mental depression can be a source of some serious illness, which can be very distressing.