Perpetual devotion to what a man calls his business, is only to be sustained by perpetual neglect of many other things.

Robert Louis Stevenson (1850-1894) Scottish essayist, novelist, poet

Essay (1877-07), “An Apology for Idlers,” Cornhill Magazine, Vol. 36
    (Source)

Collected in Virginibus Puerisque and Other Papers, ch. 3 (1881).