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, a quality of the imagination, a vigor of the emotions, it is the freshness of the deep spring of life.
青春不是年华，而是心境；青春不是桃面、丹唇、柔膝，而是深沉的意志、恢宏的想象、炽热的感情；青春是生命的深泉在涌流。

Youth means a temperamental 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.
青春气贯长虹，勇锐盖过怯弱，进取压倒苟安。如此锐气，二十后生有之，六旬男子更多见。年岁有加，并非垂老；理想丢弃，方堕暮年。

Years may wrinkle the skin, but to give up enthusiasm wrinkles the soul. Worry, fear, self-distrust bows the heart and turns the spirit back to dust. Whether 60 or 16, there is in every human being's heart the lure of wonders, the unfailing childlike appetite of what's next and the joy of the game of living. 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 the infinite, so long as you are young.
岁月悠悠，衰微只及肌肤；热忱抛却，颓唐必至灵魂。忧烦、惶恐、丧失自信，定使心灵扭曲，意气如灰。 无论年届花甲，抑或二八芳龄，心中皆有生命之欢乐，奇迹之诱惑，孩童般天真久盛不衰。人人心中皆有一个无线电台，只要你从天上人间接收美好、希望、欢乐、勇气和力量的信号，你就青春永驻，风华常存。

When the aerials are down, and your spirits are covered with snows of cynicism and the ice of pessimism. Then you've grown old even at 20, but as long as your aerials are up to catch waves of optimism, there's hope you may die young at 80.
一旦天线降下，锐气便被冰雪覆盖，玩世不恭、自暴自弃油然而生，即便年方二十，实已垂垂老矣；然则只要竖起天线，捕捉乐观的信号，你就有望在八十高龄告别尘寰时仍觉年轻。
————王佐良译