Health is not just keeping illness at bay

Health is "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity", states the preamble to the constitution of the World Health Organization, adopted in 1946.

But what is the source of health? What is well-being? And is illness always an impediment to well-being?

"Illness and health aren't opposite poles, they're two dimensions," says Joachim Kugler, a professor of health sciences and public health at Dresden University of Technology.