Online Health Psychology Certificates: Health psychology is concerned with understanding how biology, behavior, and social context influence health and illness. Health psychologists work alongside other medical professionals in clinical settings, work on behaviour change in public health promotion, teach at universities, and conduct research. Although its early beginnings can be traced to the kindred field of clinical psychology, four different divisions within health psychology and one allied field have developed over time. The four divisions include clinical health psychology, public health psychology, community health psychology, and critical health psychology.