I would say this:
"You already know what life is like WITH alcohol in your life. You already know where THIS road leads. ...
Why not see what your life is like without alcohol? Why not find out where THAT road leads?...
What if it leads to a place more wonderful then you can imagine, and you never even bothered to find out?"
That is what I told myself and what I told others as to why I was stopping drinking. It worked / works for me.