The first wealth is health. Sickness is poor-spirited, and cannot serve anyone; it must husband its resources to live. But health or fulness answers its own ends, and has to spare, runs over and inundates the neighbourhoods and creeks of other men's necessities ... Health is the first muse, comprising the magical benefits of air, landscape, and bodily exercise on the mind.... Get health; no labour, pains, temperance, poverty, nor exercise, that can gain it must be grudged. Sickness is a cannibal which eats up all the life and youth it can lay hold of, and absorbs its own sons and daughters. I figure it as a pale, wailing, distracted phantom, absolutely selfish, and afflicting other souls with meanness and mopings, and with ministration to its voracity of trifles. Dr. Johnson said severely, 'Every man is a rascal as soon as he is sick.' The best part of health is fine disposition. To make knowledge valuable you must have the cheerfulness of wisdom.
-- The Conduct of Life, by Ralph Waldo Emerson