“Half the game is mental, the other half is being mental”

Entry in progress—B.P.
 
“Ninety percent of this game is half mental” is a saying that was popular in baseball in the 1970s.
   
Wikipedia: Jim McKenny
James Claude “Howie” McKenny (born December 1, 1946 in Ottawa, Ontario) is a retired NHL defenceman and a retired Citytv sports reporter. He played 604 games between the Toronto Maple Leafs and Minnesota North Stars, and was known by the nickname of ‘Howie’ due to his resemblance to Howie Young. McKenny once said that “Half the game is mental. The other half is being mental”.
     
20 November 1980, The Star and Times (Swan River, Manitoba), “Recreation Report” by Bob Genoway, pg. 15, col. 2:
“The game of hockey is fast and rugged but half of it is mental, the other half is being mental!”
(The quote in unattributed.—ed.)
 
Google News Archive
20 January 1981, The Blade (Toledo, (OH), “Defenseman Writing Book: Diggers’ Dugan Tells All About Life In The IHL” by Dave Woolford, pg. 20, col. 1:
You’ll share in some of the great quotations by famous IHL players, such as, “When it’s pouring it’s raining,” and “half the game is mental and the other half is being mental.”
 
Google Books
Hockey Stories On and Off the Ice
By Dan Diamond, James Duplacey and Eric Zweig
Kansas City, MO: Andrews McMeel Pub.
2001
Pg. 35:
Half the game is mental, the other half is being mental.
Former Maple Leafs defenseman turned broadcaster Jim McKenney
 
Google Books
Blood & Ice:
Tales of 32 Years in the Crease
By Mike Haszto
Bloomington, IN: AuthorHouse
2010
Pg. VII:
Some of my favorite hockey quotes:
 
Jim McKenny said “Half the game is mental; the other half is being mental.”