Thinking of ninjas today (go figure) and came to the conclusion a ninja must have a great deal of confidence. A ninja must be confident in all their abilities. There can be no doubt. A ninja has a plan and executes it with no hesitation, no uncertainty. There is no room for second thoughts, what ifs. When doubt creeps up into your thoughts your odds of failing go up. Believe in your abilities, believe in yourself. Confidence is one of the many weapons in a ninja's arsenal.
*But don't get cocky cause that just annoying.