A smaller force of enthusiastic, optimistic soldiers are far more effective than a greater sized force that has no confidence in their ability to complete their mission. The smaller force's perpetual optimism is a force multiplier, making them more powerful than their pessimistic, but larger opponents.

Showing pessimism in one's abilities gives the opponent an advantage that could mean the difference between success and defeat.

Again, Napoleon sums it up succinctly. "We should always go before our enemies with confidence, otherwise our apparent uneasiness inspires them with greater boldness" (cited in Moore, 2006). This positive attitude is exactly what Powell is talking about in his explanation of...

Attitude is a significant component to success. A negative attitude can give an opponent the ever so valuable optimism that can give them the advantage of force multiplication. However, a positive, attitude on the right side, increases exponentially the effectiveness of any size force, and requires no training, no additional technology, and no geographical advantage. It is simply mental, and yet, so extremely powerful.
References

Harari, O. (2002). Leadership secrets of Colin Powell. New York: McGraw Hill.

Moore, R. (2006). Napoleon on war. Retrieved December 7, 2007, at http://www.napoleonguide.com/maxim_war.htm.

Optimism is a Force Multiplier