**2. Definitions**

### **2.1 Health**

Kazarian and Evans [2] suggest that people commonly think about health in terms of an absence of (1) objective signs that the body is not functioning properly and (2) subjective symptoms of disease or injury, such as pain or nausea. World Health Organization defined health as 'a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity' (WHO, 1946 cited in [3]:4). Some health psychologists defined health as a positive state of physical, mental and social well-being not simply the absence of injury or disease that varies over time along a continuum [4]. At the wellness end of the continuum, health is the dominant state. At the other end of the continuum, the dominant state is illness or injury, in which destructive processes produce characteristic signs, symptoms or disabilities [4]. For further detail, see **Figure 1**.

### **2.2 Health psychology**

Health psychology is a speciality within the discipline of psychology concerned with individual behaviours and lifestyles affecting physical health. The discipline strives to enhance health, prevent and treat disease, identify risk factors and improve the healthcare system public opinion regarding health issues [5]. Matarazzo in 1980 (as cited in [3]:4) offered a definition of health psychology which has become widely accepted:

*Health psychology is the aggregate of the specific educational, scientific and professional contributions of the discipline of psychology to the promotion and maintenance of health, the prevention and treatment of illness, the identification of*  *etiologic and diagnostic correlates of health, illness and related dysfunction, and the analysis and improvement of the health care system and health policy formation.*
