I am not who I was

What I am to you is not real cause you think what I was to you was more real
What I am to you, you do not need cause you think what I was to you was more needed
What I am to you is not what you mean to me cause you think I have never meant anything I do
You give me miles and miles of mountains and I ask for the sea..

Go back in time and tell me (then) of who you will be, of who you are, today and maybe I would have not changed to who I am today!