This paper has been written by Alex Jadad, who began thinking about the meaning of health and well-being in 2008, soon after becoming a patient undergoing tests to rule out a diagnosis of colon cancer. During this process, he wondered if it would be possible to have cancer and be healthy at the same time. This scenario, which seems ridiculous at first glance, forced him to realize that he did not know what "health" meant, even though he was a physician with more than 20 years of medical education, and had spent most of his adult life as a "health professional", researcher and professor in faculties that claimed to focus on health. Motivated by this realization, and aware of the inadequacy of the WHO approach, he decided to ask the question, "What is health?" in as many scenarios as possible, including a celebration of the 60th anniversary of the WHO, which was being celebrated that same year. Lacking a satisfactory answer (and with the diagnosis of cancer ruled out), he proposed to initiate a global conversation about the meaning of health to the British Medical Journal, which he coordinated for more than three years (19,20). Following a meeting in The Hague, motivated by the energy generated by the global conversation, leaders from around the world proposed a new conceptualization, which considers health to be "the ability to adapt and self-manage in the face of social, physical, and emotional challenge" (21).

The rest of this paper owes a lot to the co-authors of this work, to the people who participated in the global conversation, and to many collaborators who have used the new conceptualization since 2011 to study what causes health, to guide the completion of a pandemic of health (22), and to clarify the meaning of well-being and its implications for achieving a full life.