To be seventy years old is like climbing the Alps. You reach a snow-crowned summit, and see behind you the deep valley stretching miles and miles away, and before you other summits higher and whiter, which you may have strength to climb, or may not. Then you sit down and meditate and wonder which it will be.
To dream anything that you want to dream. That's the beauty of the human mind. To do anything that you want to do. That is the strength of the human will. To trust yourself to test your limits. That is the courage to succeed.