Steven Pressfield said this quote

“ The marine corps teaches you how to be miserable. This is invaluable for an artist. Marines love to be miserable. Marines derive a perverse satisfaction in having colder chow, crappier equipment, and higher casualty rates than any outfit of dogfaces, swabjockies, or flyboys, all of whom they despise. Why? Because those candyasses don't know how to be miserable. The artist committing himself to his calling has to be miserable. The artist committing himself to his calling has volunteered for hell, whether he knows it or not, he will be dining for the duration on a diet of isolation, rejection, self-doubt, despair, ridicule, contempt, and humiliation. The artist must be like that marine: he has to know how to be miserable. He has to love being miserable. He has to take pride in being more miserable than any soldier, or swabbie, or desk jockey, because this is war, baby, and war is hell. ”