See here for Robert Stroud (Robert Franklin Stroud) The Bird Man of Alcatraz
“Always tell yourself that you are as good as anyone that breathes; that you have two hands and a brain, and a little time in which to use them. But they are enough, and no one has any more. And if you train and force them to serve you well, you can reach any height to which you aspire. But to waste any of them is to betray yourself.”