This is an elaboration of last week's discussion. Since the modern hero (the Renaissance is sort of the dividing line between ancient and modern) is not as clear-cut as the heroes of antiquity, most modern heroes are regular people with all of the earthly concerns and weaknesses of the readers.
How, on a very human level, does Don Quixote stand for the modern, everyday hero?
One way to approach this question is to look at what Quixote stands for, what is in his heart, what he attempts (not so much what he actually accomplishes).
Another way of approaching this is to contrast Quixote (and even, to some extent, Sancho Panza) with the other characters in the book (Quixote's family, the scholar, the duke, etc.).
This is yet another way to consider this material. Since the "sane" people in the book are, for the most part, limited, mean, certainly not heroic, and since the hero (Quixote and, to a lesser extent, Panza) are mad (or simple-minded), what sort of comment might Cervantes be making about the hero in modern times? Is anybody who tries to be heroic so "different" from the rest of the society that we view that person as crazy (or at least as odd)? Does the hero have to exist apart from what is considered socially normal?
Here are a few VERY DIFFERENT examples you might want to consider for this question:
The aged super hero in "Kryptonite" by 3 Doors Down (if you've not seen the music video, then move on :)
Any sports hero
From popular culture, Batman or Superman (any super hero will do)
Mother Theresa