I believe the lack of zest and of fruitful purpose itself has physiological causes.... Any man who contemplates writing a book or engaging in any forms of preaching or propaganda should be obliged to do an hour's digging or other outdoor manual work before breakfast. By that time breakfast would be such a delight that throughout the rest of the day he would be incapable of thinking that all is vanity.
Source: "Why are we discontented?" [From: Mortals and Others: Bertrand Russell's American Essays, 1931-1935, v.1 (1975)]
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