Today we give our thanks, most of all, for the ideals of honor and faith we inherit from our forefathers — for the decency of purpose, steadfastness of resolve and strength of will, for the courage and the humility, which they possessed and which we must seek every day to emulate. As we express our gratitude, we must never forget that the highest appreciation is not to utter words but to live by them.
Let us therefore proclaim our gratitude to Providence for manifold blessings — let us be humbly thankful for inherited ideals — and let us resolve to share those blessings and those ideals with our fellow human beings throughout the world.

John F. Kennedy: "Proclamation 3560 - Thanksgiving Day, 1963," November 5, 1963. Online by Gerhard Peters and John T. Woolley, The American Presidency Project.

John F. Kennedy: Proclamation 3560 - Thanksgiving Day, 1963