Canada Month, June 1963. A later satirical version of this saying added to the end "Luckily, this is not difficult" (Paul Dickson, The Official Rules [1978]). See Eleanor Roosevelt 2
Paul Dickson (2014). “The Official Rules: 5,427 Laws, Principles, and Axioms to Help You Cope with Crises, Deadlines, Bad Luck, Rude Behavior, Red Tape, and Attacks by Inanimate Objects”, p.55, Courier Corporation
More Than Somewhat (1937). This quotation is associated with Runyon, but the Chicago Tribune, 10 May 1936, printed the following: "'The race is not always to the swift, nor the battle to the strong, but that is the way to bet,' as Hugh Keough used to say." Keough was a Chicago journalist.