Health is not merely the absence of disease. It also includes the ability to cope with stress. If you believe that you can handle difficult situations, this will have a positive impact on your actual coping skills, and you’ll be able to deal with whatever life throws your way. To feel in control is important for our ability to handle stress. This means that if you find yourself believing that there is nothing you can do, this can easily cause a lot of additional stress and impair your well-being.
Health is more than physical well-being, it also includes thoughts and feelings. It is equally important to take care of your mental health, as it is to take care of your body.
From the leaflet Simple Advice by the Norwegian Ministry of Health.