Don Quixote lived in a village in La Mancha. He was nearly 50 years old, and very skinny.
He loved books so much that he sold most of his farmable land to buy more books. He enjoyed reading fairy tales about love and quests of bravery. He often stayed up late into the night attempting to understand the passages he read that day.
He decided to venture out on his own quest, like those he had read about in his books. In order to become more honorable, he would travel the world on horseback and complete whatever quests came his way.
Don Quixote fixes up some old armor with some cardboard so he can look the part too. He also knows from his readings that every knight needs a woman to fall in love with him, so he claims some random girl from a nearby town as his "princess."
Don Quixote finds a trusty sidekick named Sancho Panza. Sancho knows the guy is crazy, but has hopes that he will be rewarded with money and riches if he follows Don Quixote on his quest.
He attacks and slays some "giants," but turns out they were actually just windmills.