O'Brien and Civil Disobedience
Tim O'brien does not believe the image that he is a "courageous" hero.
He calls this vision of himself a "pipe dream." He explicitly tells the reader that the reason he joins the war is quite simply "because [he] was embarrassed not to."
He is unable to let go of the weight of his past. The pressure he experiences in his chest is, on an energetic level, simply the amalgamation of attachments, memories, images, and emotions of his past. He cannot let them go or release them from his heart. He specifically tells us that he cannot say goodbye to his family, friends, acquaintances, hometown, and nation.
He can not, as Joseph Campbell would say, take the first step of the Hero's Journey and depart into the unknown. He is filled with shame and embarrassment at the prospect of avoiding the war. O'brien knows, as Thoreau says, that the war is a "damnable business." O'brien's struggle shows us how powerful the pressure of mass consensus can be and how much it can twist the moral compass and mind of a man. What Thoreau calls "undue respect for the law" might be more accurately rephrased here as the "undue pressure of mass consensus."
Furthermore, because O'brien is focused primarily on avoidance and does not envision himself as a hero, who focuses on right action for himself, he is unable to cross into Canada.
He asks the reader, "What would you do?" We are faced with the overwhelming weight of his question and decision. How many people would be willing to give up everything they know to avoid doing something they felt was wrong, but were obligated to do under the pressure of their entire community?