Immortality the reward of toil in preference to pleasure. Xenophon tells us when Hercules was a youth he was accosted by two women—Virtue and Pleasure—and asked to choose between them. Pleasure promised him all carnal delights, but Virtue promised immortality. Hercules gave his hand to the latter, and, after a life of toil, was received amongst the gods.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894