mental health is different from physical health which we can see and feel it directly. mental health is a state of our inner heart,whether we are positive,active or depressed or feel blue.
mental illness includes melancholia (忧郁症),
obsession（强迫症） and so on .
physical health refers to that if your body can work healthily , normally , efficiently.
physical illness includes cold,flu,injury,wound in an accident or other kind of illness.