How do you get rid of a forming hunchback?

I have been slouching for a bit, and don't have very good posture. today my mom told me that i am starting to have a little too much of a curve in my neck, but i don't have a hunchback really, just the very beginnning of one. I have a wedding to attend in two weeks, and i don't want to show up with a hunchback. What is the quickest way to get rid of something that is starting to appear?