To me the definition of heath is a state of being for the body where it is able to function unimpeded at optimum levels and without adverse effects. Then illness is the physiological manifestation that can arise from a sickness or injury, like if you have the flu your illness is presented by how you feel about your symptoms.
To me cancer is an illness, because the tumor is the physical manifestation brought on by the unimpeded replication of cells that occurs when there is a defect in a cells genetic code that leaves it with the reproduction switch flipped on. Even though most people label cancer as the disease it is really the byproduct of a underlying problem. We see the tumor on the CAT scan and people tend to see that as the problem because they can’t see the individual cells that are reproducing out of control. So in an attempt to rationalize something they don’t completely understand they label the tumor as the problem not the result of the underlying condition. But it is not an illness because a person can have cancer for a long time with no knowledge of their problem.
This was a tricky one for me but old age by my own definition is actually an illness which is very weird for me to think of it that way. Because in my own head old age is normal and we tend to think of an illness as something that is out of place. Something that is not natural and that needs to be corrected. So this revelation actually made me think of illness in a new light. Because by my own definition old age is a physiological manifestation of a long life of being exposed to various things that can cause small changes in our bodies. Which makes us “feel” old with aches and pains that give us the physiological thought of being old.