I feel like I'm trapped in someone else's body?

I've been in the Navy almost a year and a half, and I hate it so much to the point I've become depressed I think. I hate going outside my barracks. I went from smoking half a pack to a full pack. No one wants to listen. They all say that I will change my mind or that I haven't had enough time in to form an opinion or that time will fly by. It's not. I feel like I'm trapped in someone else's body. There is no way out. It's not who I am at all. I don't even have the same views as the military. While all my friends are going into their junior year in college, I am sweeping floors. When my friends will be successful businessman, I will be a sophomore. What can I do to hang on for the next 2 1/2 years.