Belief in oneself is incredibly infectious. It generates momentum, the collective force of which far outweighs any kernel of self-doubt that may creep in.
No! I am not Prince Hamlet, nor was meant to be; Am an attendant lord, one that will do To swell a progress, start a scene or two, Advise the prince; no doubt, an easy tool, Deferential, glad to be of use, Politic, cautious, and meticulous; Full of high sentence, but a bit obtuse; At times, indeed, almost ridiculous— Almost, at times, the Fool.
Everyone who observes himself doubting observes a truth, and about that which he observes he is certain; therefore he is certain about a truth. Everyone therefore who doubts whether truth exists has in himself a truth on which not to doubt.... Hence one who can doubt at all ought not to doubt the existence of truth.