“May all your troubles last as long as your New Year's resolutions.”

Source: Moonchild

Source: Wolves of the Calla

Source: Stargirl

Address at Princeton University, "The Educated Citizen" (22 March 1954).
Variant: It is not the years in your life but the life in your years that counts.
"If I Were Twenty-One" in Coronet (December 1955).
This has also been paraphrased "What matters most is not the years in your life, but the life in your years" and misattributed to Abraham Lincoln and Mae West
Context: All progress has resulted from people who took unpopular positions. All change is the result of a change in the contemporary state of mind. Don't be afraid of being out of tune with your environment, and above all pray God that you are not afraid to live, to live hard and fast. To my way of thinking it is not the years in your life but the life in your years that count in the long run. You'll have more fun, you'll do more and you'll get more, you'll give more satisfaction the more you know, the more you have worked, and the more you have lived. For yours is a great adventure at a stirring time in the annals of men.

Introductio ad prudentiam: Part II (1727), Gnomologia (1732)

Letter to Fanny Brawne (March 1820)
Letters (1817–1820)