Youth is not a time of life; it is a state of mind. It is not a matter of red cheeks, red lips and supple knees. It is a temper of the will; a quality of the imagination; a vigor of the emotions; it is a freshness of the deep springs of life. Youth means a tempermental predominance of courage over timidity, of the appetite for adventure over a life of ease. This often exists in a man of fifty, more than in a boy of twenty. Nobody grows old by merely living a number of years; people grow old by deserting their ideals. Years may wrinkle the skin, but to give up enthusiasm wrinkles the soul. Worry, doubt, self-distrust, fear and despairthese are the long, long years that bow the head and turn the growing spirit back to dust. Whether seventy or sixteen, there is in every beings heart a love of wonder; the sweet amazement at the stars and starlike things and thoughts; the undaunted challenge of events, the unfailing childlike appetite for what comes next, and the joy in the game of life. You are as young as your faith, as old as your doubt; as young as your self-confidence, as old as your fear, as young as your hope, as old as your despair. In the central place of your heart there is a wireless station. So long as it receives messages of beauty, hope, cheer, grandeur, courage, and power from the earth, from men and from the Infiniteso long are you young. When the wires are all down and the central places of your heart are covered with the snows of pessimism and the ice of cynicism, then are you grown old, indeed!  

Source: SAMUEL ULLMAN, Youth.Jane Manner, The Silver Treasury, Prose and Verse for Every Mood, pp. 32324

 以下是我比较喜欢的一个译本：

  青春，不是人生的一个时期，而是一种心态。
  青春的本质，不是粉面桃腮，不是朱唇红颜，也不是灵活的关节，而是坚定的意志，丰富的想象，饱满的情绪，也是荡漾在生命甘泉中的一丝清凉。
  青春的内涵，是战胜怯懦的勇气，是敢于冒险的精神，而不是好逸恶劳。许多六旬之人，反比廿岁的人更具如此品质。年岁虽增，却并不衰老；衰老的成因，是放弃了对理想的追求。
  岁月褶皱皮肤，暮气却能褶皱灵魂。烦恼、恐惧，乃至自疑，均可摧垮精神，伤害元气！
  人人心中，都有一部无线电台。只要能从他人或造物主那里收到美好、希望、欢畅、勇敢和力量的信息，我们便拥有春天。
  一旦天线弯折，精神便会遭到愤世和悲观的冰霜的镇压。此时，即使20岁的人，也会觉得老了；然而，只要高竖天线，不断接收乐观向上的电波，那么，即使你年过80岁，也仍觉年轻。