It is of course much pleasanter if one is naturally fearless, and I envy and respect the men who are naturally fearless. But it is a good thing to remember that the man who does not enjoy this advantage can nevertheless stand beside the man who does, and can do his duty with the like efficiency, if he chooses to. Of course he must not let his desire take the form merely of a day-dream.
 Theodore Roosevelt, Theodore Roosevelt; an Autobiography (1913). copy citation

Context

“They will first learn to bear themselves well in trials which they anticipate and which they school themselves in advance to meet. After a while the habit will grow on them, and they will behave well in sudden and unexpected emergencies which come upon them unawares. It is of course much pleasanter if one is naturally fearless, and I envy and respect the men who are naturally fearless. But it is a good thing to remember that the man who does not enjoy this advantage can nevertheless stand beside the man who does, and can do his duty with the like efficiency, if he chooses to. Of course he must not let his desire take the form merely of a day-dream. Let him dream about being a fearless man, and the more he dreams the better he will be, always provided he does his best to realize the dream in practice. He can do his part honorably and well provided only he sets fearlessness before himself as an ideal, schools himself to think of danger merely as something to be faced and overcome, and regards life itself as he should regard it, not as something to be thrown away, but as a pawn to be promptly hazarded whenever the hazard is warranted by the larger interests of the great game in which we are all engaged.” source