“Middle age is when work is a lot less fun and fun a lot more work” is a jocular saying that has been printed on many images. “As one gets older, work seems a lot less fun and fun seems a lot more work” was cited in a 1954 newspaper. Authorship is unknown.
 
“Middle age is the time of life when work beings to be a lot less fun, and fun begins to be a lot more work” was cited in a 1970 newspaper.
   
“You can tell you’re getting old when work is a lot less fun and fun is a lot more work” has been credited to Brooklyn-born comedian Joan Rivers (1933-2014) since at least 2005.
   
   
Old Fulton NY Post Cards
29 October 1954, The News-Messenger (Hamlet, NC), “So This Is New York” by North Callaman, pg. 2, col. 3:
As one gets older, work seems a lot less fun and fun seems a lot more work.
 
22 November 1955, The News and Courier (Charleston, SC), “Doing The Charleston” by Ashley Cooper, pg. 8-A, col. 4:
Q. Is it true that as people get older, work seems a lot less fun? (College of Charleston soph.)
A. Yes, and fun seems a lot more work.
   
3 April 1956, Milwaukee (WI( Journal, Green Sheet, pg. 1 banner:
As You Get Older Work Is a Lot Less Fun, and What’s Worse, Fun Is a Lot More Work
 
27 May 1956, Los Angeles (CA) Times, “Country Flavor” by Kerwin Hoover, pt. 2, pg. 5, col. 1:
Everett Remsburg of the Vista Press of the Vista Press admits that as he grows older work does seem a lot less fun and fun a lot more work.
 
13 July 1956, Pittsburgh (PA) Post-Gazette, “It Happened Last Night” by Earl Wilson, Daily Magazine, pg. 1, col. 7:
EARL’S PEARLS…“You;re growing older when work seems a lot less fun, and fun a lot more work.”
 
7 January 1964, Burlington (VT) Free Press, “The Old-Timer Says,” pg. 10, col. 3:
Somehow or other, as we get older, work seems a lot less fun and fun seems a lot more work.
 
7 April 1970, Rockford (IL) Register-Republic, Pg. A2, col. 7:
Middle age is the time of life when work beings to be a lot less fun, and fun begins to be a lot more work.
     
Google Books
Speaker’s & toastmaster’s Handbook
By Herbert V. Prochnow
Rocklin, CA: Prima Pub.
1993
Pg. 161:
Somehow or other, as we get older, work seems a lot less fun, and fun seems a lot more work.
 
Google Books
20,000 Quips & Quotes
By Evan Esar
New York, NY: Barnes & Noble Books
1995, ©1968
Pg. 21:
As we grow older, work seems a lot less fun, and fun seems a lot more work.
     
9 April 2005, The Sun (London, UK), “Royal fiasco? You ain’t seen nothing” by Sergei Platt, pg. 34:
IT’S hard to figure out why JOAN RIVERS is at the big wedding - unless she’s booked to do a turn.
 
She might be tempted to tell her gag: “You can tell you’re getting old when work is a lot less fun and fun is a lot more work.”
 
Google Books
The Quote Manual:
Wisdom and Wit of the Ages
By Robert G. Moscatelli
BLoomington, IN: AuthorHouse
2012
Pg. 201:
“You know you are getting old when work is a lot less fun and fun is a lot more work.”
Joan Rivers
Comedienne
     
Google Books
Of Wit N Humour
By Vincent Thnay
Lulu Publishing (Lulu.com)
2015
Pg. ?:
Middle age is when work is a lot less fun and fun a lot more work. - Unknown