We've all read books that changed our lives but one college professor gets more than he bargains for when he picks up a dusty, dog-eared copy of the American classic Walden by Henry David Thoreau.   Proud postmodern consumer and card-carrying member of the "I Hate Nature" Club, Michael Gurnow is content in his role as American literature professor at a Midwest college.   Everything changes once he gets done reading Thoreau's masterpiece.  Realizing he has been living a life of quiet desperation, it suddenly occurs to him that even though it's his job to teach tales of other people's adventures, he hasn't lived any of his own. Without a second thought, Gurnow hands in his resignation before driving to the nearest state park and applies to be the wilderness equivalent of a construction worker.