Health is the ability of a biological system to acquire, convert, allocate, distribute, and utilize energy with maximum efficiency. The World Health Organization (WHO) defined human health in a broader sense in its 1948 constitution as "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity." This definition has been subject to controversy, in particular as lacking operational value, the ambiguity in developing cohesive health strategies and because of the problem created by use of the word "complete", which makes it practically impossible to achieve. Other definitions have been proposed, among which a recent definition that correlates health and personal satisfaction.
Health psychology is the study of psychological and behavioral processes in health, illness, and healthcare. It is concerned with understanding how psychological, behavioral, and cultural factors contribute to physical health and illness. Psychological factors can affect health directly. For example, chronically occurring environmental stressors affecting the hypothalamic–pituitary–adrenal axis, cumulatively, can harm health. Behavioral factors can also affect a person's health. For example, certain behaviors can, over time, harm (smoking or consuming excessive amounts of alcohol) or enhance health (engaging in exercise). Health psychologists take a biopsychosocial approach. In other words, health psychologists understand health to be the product not only of biological processes (e.g., a virus, tumor, etc.) but also of psychological (e.g., thoughts and beliefs), behavioral (e.g., habits), and social processes (e.g., socioeconomic status and ethnicity).
Psychology is the science of behavior and mind, including conscious and unconscious phenomena, as well as feeling and thought. It is an academic discipline of immense scope and diverse interests that, when taken together, seek an understanding of the emergent properties of brains, and all the variety of epiphenomena they manifest. As a social science it aims to understand individuals and groups by establishing general principles and researching specific cases.
We cannot describe how the mind is made without having good ways to describe complicated processes. Before computers, no languages were good for that. Piaget tried algebra and Freud tried diagrams; other psychologists used Markov Chains and matrices, but none came to much. Behaviorists, quite properly, had ceased to speak at all. Linguists flocked to formal syntax, and made progress for a time but reached a limit: transformational grammar shows the contents of the registers (so to speak), but has no way to describe what controls them. This makes it hard to say how surface speech relates to underlying designation and intent–a baby-and-bath-water situation. I prefer ideas from AI research because there we tend to seek procedural description first, which seems more appropriate for mental matters.
Marvin Minsky, in "Music, Mind, and Meaning" (1981)
For it still seemed to me “that it is not we who sin, but some other nature sinned in us.” And it gratified my pride to be beyond blame, and when I did anything wrong not to have to confess that I had done wrong. … I loved to excuse my soul and to accuse something else inside me (I knew not what) but which was not I. But, assuredly, it was I, and it was my impiety that had divided me against myself. That sin then was all the more incurable because I did not deem myself a sinner.
Augustine, Confessions, A. Outler, trans. (Dover: 2002), p. 77
[Modern psychology] appears as the sickly offspring of average common sense when it is taken as what it professes to be—a science of the inner life. The entire achievements of the so-called science in this respect is outweighed by a single page of Goethe’s or of Jean Paul’s psychology; and it is impossible to evade the bitter truth which Novalis already has summed up, when he says that so-called psychology is one of those idols which have usurped the place in the sanctuary where true images of the gods should stand.
Ludwig Klages, The Science of Character, W. Johnston, trans., p. 16