“Get fit to play sports—don’t play sports to get fit” (or “Get in shape to play sports—don’t play sports to get in shape”) is a frequently cited sports and exercise adage. Sports are strenuous and participants should already be in shape before playing.
 
“You don’t play sports to get into shape—you get into shape to play sports” has been cited in print since at least 1975. A 1993 book (see below) attributes the saying to Dr. Fred Allman, a one-time president of the American College of Sports/Medicine, but this has not been confirmed by citational evidence.
   
 
23 October 1975, Christian Science Monitor, “The ‘Ross Hunter touch’” by Arthur Unger, Arts/Entertainment, pg. 19:
According to “The Weekend Athletes” (ABC, Friday, 10-11 pm, check local listings ), you don’t play sports to get into shape—you get into shape to play sports.
 
24 October 1975, Boston (MA) Globe, “Hope springs as eternal star in NBC special” by Percy Shain, pg. 33:
Its thrust is best summed up by Bergman with the words, “You don’t play sports to get into shape; you get into shape to play sports.”
 
Google Books
Fitness and Work Capacity
By Brian J. Sharkey, United States Forest Service
Washington, DC: Dept. of Agriculture, Forest Service: For sale by the Supt. of Docs., U.S. Govt. Print. Off.
1977
Pg. 21:
DON’T PLAY SPORTS TO GET IN SHAPE.
GET IN SHAPE TO PLAY SPORTS.
 
15 November 1980, Lethbridge (Alberta) Herald, “Winter Warmup” by Gordon W. Stewart, Today, pg. 36, col. 3:
An old exercise adage warns, “Get fit to play sports, don’t play sports to get fit.”
 
13 July 1982, The Register (Orange County, CA), “Bodybuilder says women have nothing to fear from lifting weights,” pg. C3, col. 4:
You don’t play sports to get in shape, you get in shape to play sports.
         
Google Books
Soft Steps to a Hard Body
By Ellington Darden
Dallas, TX: Taylor Pub. Co.
1993
Pg. 67:
As stated many years ago by Dr. Fred Allman, a one-time president of the American College of Sports/Medicine, “Don’t play sports to get into shape. Get into shape to play sports.”
 
Google Books
Shape Up!:
A Fitness Handbook
By Bud Getchell
Indianapolis, IN: Masters Press
1994
Pg. ?:
You need to get in shape to play sports, rather than play sports to get in shape.
 
Google Books
Sport Physiology for Coaches
By Brian J. Sharkey and Steven E. Gaskill
Champaign, IL: Human Kinetics
2006
Pg. 198:
He recited the quote “Don’t play sports to get in shape, get in shape to play sports.”
 
Google Books
Concepts of Athletic Training (6th edition)
By Ronald P. Pfeiffer and Brent C. Mangus
Sudbury, MA: Jones & Bartlett Learning
2011, ©2012
Pg. 44:
The old saying “You don’t play sports to get fit, you get fit to play sports” is certainly valid today.