“It doesn’t matter how much milk you spill, just so long as you don’t lose the cow” was popularized by business author Harvey Mackay, who used this line in his book, Swim With the Sharks: Without Being Eaten Alive: Outsell, Outmanage, Outmotivate, and Outnegotiate Your Competition (1988). Evangelical Christian author John C. Maxwell has also used the saying in his books.
 
It’s not certain where the saying originated; it has sometimes been claimed as an “old Texas saying.” “Don’t grieve about the milk you spill/ While there are cows and clover!” was cited in the Atlanta (GA) Constitution in 1895.
 
 
7 July 1895, Atlanta (GA) Constitution, pg. 14, col. 6:
Cheer Up!
Keep your old heart happy still—
Time’s a reckless rover;
Don’t grieve about the milk you spill
While there are cows and clover!
 
30 April 1989, The Plain Dealer (Cleveland, OH), pg. 5-H. col. 2:
The ultimate test in dominance is, of course, war, which surfaces even in Harvey Mackay’s “Swim With the Sharks,” the least militaristic of the advice manuals. The book offers advice that is never devious or dishonest and that frequently serves up such folk wisdom as: “It doesn’t matter how many pails of milk you spill, just so long as you don’t lose the cow.”
     
Newspapers.com
12 May 1991, Battle Creek (MI) Enquirer, “Making a small Scene” by David Carlton, pg. 1C, col. 4:
It doesn’t matter how many pails of milk you spill, as long as you don’t lose the cow.
   
20 November 1994, Denver (CO) Post, “Aphorisms II: More words to live by” by Harvey Mackay, Business, pg. I-10:
*I don’t care how many pails of milk I lose, as long as I don’t lose the cow.”
   
Newspapers.com
19 May 1995, Evansville (IN) Courier, “Winners know when to say when” by Harvey Mackay, pg. C7, col. 6:
Mackay’s Moral: It doesn’t matter how much milk you spill as long as you don’t lose the cow.
     
Google Books
What to Do When You Don’t Know What to Do
By Neil Eskelin
Palos Verdes, CA : Western Front
1995
Pg. 119:
“It doesn’t matter how much milk you spill as long as you don’t lose your cow. ” — East Texas saying
 
Google Books
Why Climb the Corporate Ladder When You Can Take the Elevator?:
500 Secrets for Success in Business
By John M. Capozzi
Fairfield, CT: JMC Industries
1997, ©1994
Pg. ?:
24.
It doesn’t matter how many pails of milk you spill, just don’t lose the cow.
   
Newspapers.com
26 July 1998, Fresno (CA) Bee, “Managing People” by Harvey Mackay, pg. C4, col. 1:
There’s an old East Texas saying that I’ve adopted: “It doesn’t matter how much milk you spill just so long as you don’t lose the cow.”
 
Google Books
Failing Forward:
Turning Mistakes Into Stepping Stones for Success
By John C. Maxwell
Nashville, TN: Thomas Nelson
2000
Pg. ?:
5. People Think Failure Is Irreversible—It’s Not
There’s an old saying in Texas: “It doesn’t matter how much milk you spill as long as you don’t lose your cow.” In other words, mistakes are not irreversible.
 
New York (NY) Times
Toolkit
Some Inspiration to Make 2010 a Success
By PAUL B. BROWN
Published: January 5, 2010
(...)
Consider the seemingly endless number of speakers, everyone from the Rev. Billy Graham to John C. Maxwell, the author of books on leadership, who have cited what they say is an old Texas expression, “It doesn’t matter how much milk you spill, as long as you don’t lose the cow.”
 
William E Wood and Associates, Realtors 
“What Failure is NOT”
June 25, 2013
(...) 
To those of you who are faced with challenges let me offer these words of encouragement from one of my most admired authors, John Maxwell. He says, “Failure is simply a price we pay to achieve success.” According to Maxwell there are several things that failure is NOT:
(...) 
People think failure is irreversible…it’s not.  There is an old Texas saying, “It doesn’t matter how much milk you spill as long as you don’t lose the cow.” In other words, keep the big picture perspective.
   
Twitter
Steve Burns
@SJosephBurns
“It doesn’t matter how much milk you spill as long as you don’t lose your cow.” (Old Texas saying)
7:24 AM · Nov 23, 2022·Twitter for iPhone