Orwell notes the ambiguity in "work" and "play"

But what is work and what is not work? Is it work to dig, to carpenter, to plant trees, to fell trees, to ride, to fish, to hunt, to feed chickens, to play the piano, to take photographs, to build a house, to cook, to sew, to trim hats, to mend motor bicycles? All of these things are work to somebody, and all of them are play to somebody. There are in fact very few activities which cannot be classed either as work or play according as you choose to regard them. The labourer set from digging may want to spend his leisure, or part of it, in playing the piano, while the professional pianist may be only too glad to get out and dig at the potato patch. Hence the antithesis between work, as something intolerably tedious, and not-work, as something desirable, is false. The truth is that when a human being is not eating, drinking, sleeping, making love, talking, playing games or merely lounging about—and these things will not fill up a lifetime—he needs work and usually looks for it, though he may not call it work.

George Orwell, The Road to Wigan Pier (New York: Harcourt, Brace & Co., 1958), p. 229 (1st U.S. ed.; pub. in England in 1937)

Brandeis recommends recreation

Brandeis learned a lesson that he would practice and preach to others all his life, namely, that unless one found some way to exercise the body as well as the mind, one could not do good work. As a young lawyer he belonged to a riding club, and later took up canoeing. He also took regular vacations, and all of August off. “I learned that I could do a year’s worth of work in eleven months, but not in twelve.” Brandeis’s insistence on taking time off involved not just health; he understood that a tired person more easily made mistakes, not just of fact but of judgment as well. 

Melvin I. Urofsky, Louis D. Brandeis: A Life (New York: Pantheon, 2009), p. 34

After one walk, Brandeis told his wife “that while the dog had behaved reasonably well, he ‘has occasional lapses from virtue which convince me he should be muzzled. He does bite sometimes & we shall have claims made against us if we don’t act soon.’” Id. at 361.

The fun of watching others work

'I think the most joyous thing in life is to loaf round and watch another bloke doing a job of work. Look how popular the men are who dig up London with electric drills. Duke's son, cook's son, son of a hundred kings—people will stand there for hours on end, with their ear-drums splitting—why? Simply for the pleasure of being idle while other people work.' 

Dorothy L. Sayers, The Five Red Herrings (London: Hodder & Stoughton, 2003), Kindle location 3800 (orig. pub. 1931).