And it is very much easier to forget work at the times when it ought to be forgotten if a man has many interests other than his work than it is if he has not. It is, however, essential that these interests should not exercise those very faculties which have been exhausted by his day's work. They should not involve will and quick decision, they should not, like gambling, involve any financial element, and they should as a rule not be so exciting as to produce emotional fatigue and preoccupy the subconscious as well as the conscious mind.
Source: The Conquest of Happiness, 1930, chap. 15：Impersonal interests
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