The word health to me would be the idea of completeness and well-being, mind and body at its full operating ability without fault. Which includes absence of disease or injury. What I would consider as a illness is a defect in operation or function in a certain area or entire body including a persons metal capacity. My ideas are based off of studying the human body and its functioning, from school and experiences with doctors. It just makes sense that when a body is properly maintained and cared for, it will work at its best capacity.
I believe that this is an illness that can range in severity. Suffering from mild ADHD myself I know it can be extremely hard to focus or sit still. In some situations its impossible. For someone who has severe ADHD I could see it affecting almost every aspect of their life, obviously able to be considered a disability. Not to mention the inability to function from the medications prescribed to treat severe ADHD, the clients turn lethargic and process much slower. Under the influence of these drugs it becomes harder to learn and students are then said to have a learning disability.
Depression is another illness that can be treated with medication, in a sense to help a person return to a healthy state of mind without the medication in the future. It defiantly is a illness because once again this is a mental issue that can effect every aspect of life. Severe depression can lead to suicidal behavior and is a mental illness that must be treated and maintained long-term. Without long-term observation it is very easy for the patient to return to a depressed mental state. Depression can lead to other mental illness that can affect daily life such as panic disorders and anxiety.