Samuel Ullman — American Poet

Samuel Ullman was an American businessman, poet, humanitarian. He is best known today for his poem Youth which was a favorite of General Douglas MacArthur. The poem was on the wall of MacArthur's office in Tokyo when he became Supreme Allied Commander in Japan. In addition, MacArthur often quoted from the poem in his speeches, leading to it becoming better known in Japan than in the United States... (wikipedia)

Maturity is the ability to think, speak and act your feelings within the bounds of dignity. The measure of your maturity is how spiritual you become during the midst of your frustrations.
Youth is not a time of life; it is a state of mind; it is not a matter of rosy cheeks, red lips and supple knees; it is a matter of the will, quality of the imagination, a vigor of the emotions; it is the freshness of the deep springs of life.
Nobody grows old merely by living a number of years. We grow old by deserting our ideals. Years may wrinkle the skin, but to give up enthusiasm wrinkles the soul.
You are as young as your self-confidence, as old as your fears; as young as your hope, as old as your despair.
When the wires are all down and your heart is covered with the snows of pessimism and the ice of cynicism, then, and only then, have you grown old.