“There’s no time to rest when there’s work to be done. Eat on the run, forget about sleep, and change horses often” is sometimes described as a Texas proverb or an old-time cowboy proverb, but there is no evidence that this was used in the old west. The saying first appeared in Don’t Squat with Your Spurs On!: A Cowboy’s Guide to Life (1992), by Texas Bix Bender.
 
   
Google Books
Don’t Squat with Your Spurs On!:
A Cowboy’s Guide to Life
By Texas Bix Bender
Layton, UT: Gibbs Smith
1992
Pg. 66:
THERE’S NO TIME TO REST
when there’s work to be done. Eat on the run, forget about sleep, and change horses often.
   
TheShootists.co.uk Forum
Muleskinner
Posted 12/04/05
(...)
There’s no time to rest when there’s work to be done. Eat on the run, forget about sleep, and change horses often.
 
Twitter
shuvo chatterjee‏
@shuvster  
“There’s no time to rest when there’s work to be done. Eat on the run, forget about sleep, and change horses often.” - Texas proverb
1:28 PM - 27 Nov 11 from Lubbock, TX
   
Fox News
Cowboy wisdom for GOP and Democratic conventions
By Patrick Dorinson
Published August 24, 2012
(...)
For Mitt Romney and Paul Ryan…
There’s no time to rest when there’s work to be done. Eat on the run, forget about sleep and change horses often.