“Don’t watch the clock; do what it does. Keep going!”

“Don’t watch the clock; do what it does Keep going!” has been printed on many posters, with credit usually given to Brooklyn-born humorist Sam Levenson (1911-1980). Levenson included the saying in his book, You Don’t Have to Be in Who’s Who to Know What’s What (1979).
     
 
Wikipedia: Sam Levenson
Sam Levenson (December 28, 1911 – August 27, 1980) was an American humorist, writer, teacher, television host, and journalist.
       
Hathi Trust Digital Library
OCLC WorldCat record
You don’t have to be in Who’s who to know what’s what
Author: Sam Levenson
Publisher: New York : Simon & Schuster, ©1979.
Edition/Format:   Print book : English
 
Google Books
Words of Wisdom
Edited by William Safire and Leonard Safir
New York, NY: Simon & Schuster
1989
Pg. 398:
Don’t watch the clock; do what it does. Keep going. — Sam Levenson
 
10 January 2002, Daily Republican Register (Mt. Carmel, IL), pg. 1, col. 4:
MUSINGS ON THE WABASH
Don’t watch the clock. Do what it does. Keep going. — Sam Levenson
 
17 April 2003, The Advocate (Stamford, CT), “Daily Bridge Club” by Frank Stewart, pg. C6, col. 1:
“Don’t watch the clock. Do what it does. Keep going!”—Sam Levenson.
 
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Do not watch the clock. Do what it does. Keep going.  -  Sam Levenson #quote
12:33 PM - 21 Mar 2015