Eddie realizes by the end of his narrative that he cannot stay in Fresno and expect to find a future. It becomes clear Fresno is filled with too much pain and too much weight in Eddie's past. Eddie understands that Fresno is fraught with so many threats that his desire in "trying to run a straight line" will not be recognized. It is for this reason that he wishes to live with his mother in Merced. She will not take him.
With these realities, Eddie understands that the Navy is his only option. In several respects, this makes sense. Eddie seeks "to run a straight line" and wishes to be productive. Fresno is a unstructured and chaotic setting. The Navy provides discipline, order, and structure. This is beneficial to Eddie. Additionally, the Navy allows Eddie to physically escape from Fresno. Being able to leave Fresno through the Navy will allow Eddie to focus on establishing an identity that is outside of the setting that spells so much in way of suffering and pain. If one were to find a potential fault in Eddie going into the Navy, it would be the reality of seeing military conflict and action. Eddie seeks to find a way out from death and the lack of opportunity. If Eddie would be committed to military service, perhaps this might be something that would not be overall beneficial to him. Yet, I think that Eddie entering into the Navy is on the whole beneficial for him.
I think that Eddie has shown toughness in his experiences in Fresno. Eddie has seen death, pain, hurt, and suffering. He has lived a life where he has been hunted and where he has experienced the worst in human treatment of another. Eddie has absorbed "the sadness" of one's being. This has helped toughen him to an experience such as the Navy. There is little that the armed forces can demonstrate to Eddie that he has not seen. If anything, going into the armed forces might be seen as a welcome departure from a life in Fresno of being on the run and being threatened. Eddie has become tougher through his experiences. He still envisions a better life and this can be seen in Eddie going into the Navy. When Eddie cries as he reflects "on the last of childhood tears," it is clear that he is ready to move on from this. He is ready to lose his yesterdays in exchange for some tomorrows. This is why he is tough enough to handle what the Navy will present to him.