I dont know if they really inspire me, but one I am fond of for it's lightheartedness and humor is a misquoting of Miyamoto Musashi.
"The battlefield is a venue to show what you have learned, and how well. If your opponent falters, engage him. If you falter, engage him. If both you and your opponent falter, engage him. There can only be three outcomes of a duel. One! You cut your opponent. In this case, kill him. Two! Your opponent cuts you. In this case, kill him. Three! Both you and your opponent cut each other at the same time. In this case, kill him." This is usually followed by a "RHAANNNNNN" which is echoed back by the rest.