“Success is a ladder which cannot be climbed with your hands in your pockets” is a proverb that means that one should work hard and take initiative in order to be successful. “Oh no, Alonzo, you can’t climb the ladder of success with your hands in your pockets” has been cited in print since at least 1911 and is of unknown authorship.
 
 
1 July 1911, The Daily Northwestern (Oshkosh, WI), pg. 10, col. 4:
Oh no, Alonzo, you can’t climb the ladder of success with your hands in your pockets.
 
Chronicling America
16 August 1911, San Francisco (CA) Call, pg. 11, col. 4:
Oh no, Alonzo, you can’t climb the ladder of success with your hands in your pockets.
 
3 February 1919, Fort Wayne (IN) News and Sentinel, pg. 8, col. 7:
Advice.
“The poor are often lazy men,”
Remarked old Uncle Brockets
“For you can’t climb a ladder when
Your hands are in your pockets.”
—Luke McLuke.
 
14 July 1940, Boston (MA) Herald, “Definitions: Wise and Otherwise,” This Week magazine, pg. 16, col. 5:
SUCCESS: A ladder you cannot climb with your hands in your pockets.
Collected by
Jno. Garland Pollard
Former Governor of Virginia
 
11 June 1951, Greensboro (NC) Record, “Trade Winds” by Louis Schneider, pg. B-9, col. 6:
You cannot climb the ladder of success with your hands in your pockets.
 
Google Books
How to Develop Successful Salesmen
By Kenneth Brooks Haas
New York, NY: McGraw-Hill
1957
Pg. 9:
SUCCESS: A ladder you cannot climb with your hands in your pockets.
   
Google Books
Complete Speaker’s and Toastmaster’s Library
By Jacob Morton Braude
Englewood Cliffs, NJ: Prentice-Hall
1965
Pg. 105:
Success is a ladder which cannot be climbed with your hands in your pockets.
 
Google News Archive
28 July 1966, Middlesboro (KY) Daily News, “Barbs,” pg. 8, col. 6:
It’s tough to climb the ladder of success, but it’s impossible with your hands in your pockets.
 
Google Books
The Reader’s Digest
Volume 125, Issues 747-752
1984
Pg. 137:
Success is a ladder that cannot be climbed with your hands in your pockets. — American proverb
 
Google Books
Steps to the Top
By Zig Ziglar
Gretna, LA: Pelican Publishing Company, Inc.
1985
Pg. 227:
You cannot climb the ladder of success with your hands in your pockets.
   
DutchNews.nl
How to win the Nyenrode Master Challenge: Part II - 05-12-2012
(...)
When applying for the challenge I kept a quote by Donald Trump in my mind: ‘success is a ladder that cannot be climbed with your hands in your pockets’.