Youth is not a time of life, it is a state of mind; it is not a matter of rosy（蔷薇色的） cheeks, red lips and supple knees, it is a matter of the will, a quality of the imagination, a vigor of the emotions.it is the freshness of the deep springs of life.
Youth means a tempera-mental predominance of courage over timidity, of the appetite for adventure over the love of ease. This often exists in a man of 60 more than a boy of 20. Nobody grows old merely by a number of years. We grow old by deserting our ideals.
Years may wrinkle（起皱） the skin, but to give up enthusiasm wrinkles the soul. Worry, fear, self-distrust bows the heart and turns the spring back to dust.whether 60 or 16, there is in every human being's heart the lure of wonder,the unfailing childlike appetite of what's next and the joy of the game ofliving. In the center of your heart and my heart there is a wireless station: so long as it receives messages of beauty, hope, cheer, courage and power from men and from the Infinite, you and I will remain young.
When the aerials are down, and your spirit is covered with snows of cynicism and the ice of pessimism, then you are grown old, even at 20, but as long as your aerials are upto catch waves of optimism, there is hope you may have young heart at 80.