That story which best illustrates the moral idea that incentive spurs effort is “The Hare and the Hound”.
Here is the story;
"A Hound having started a Hare from his form, after a long run, gave up the chase. A Goat-herd, seeing him stop, mocked him, saying: "The little one is the best runner of the two." The hound replied; "You do not see the difference between us; I was only running for a dinner, but he for his life."
Aesop's Fables or otherwise known as the Aesopica, is an accumulation of tales credited to Aesop, a slave and storyteller known to have lived in antiquated Greece somewhere in the range of 620 and 564 BCE.