We completely become what we completely believe.  Example:

Before I moved to South Korea at the tender age of 45, I did not believe I was handsome.  I did not think I was ugly either. I though I was average looking,  but a funny thing happened in Korea - something I never expected would happen,  an interesting side-effect: for the first time in my life people began to tell me I'm handsome.  A lot of people.  My students.  Strangers in public.  Over and over, just about every week. Guess what? I began to believe them. Then what happened still amazes me today - I became handsome! I'm much better looking now than when I arrived in Korea 14 years ago. Did I change or did the way I see myself change? I think it's both! As I believed what was said about me -  i became what I believed. For some people this happens with negative results.  They're told they're a failure. They're told they'll never amount to anything.  They're told they're ugly. And they believe it and they become what they believe!

Listen -  we do not believe with our minds. We know with our minds but we believe with our hearts - 

"For with the heart man believes unto righteousness" " If you will confess with your mouth the Lord Jesus and shall believe in your heart" Remember: "out of the abundance of the heart the mouth speaks" and "confession is made unto salvation " So, we have what we confess but we cofess what we believe.  If you believe you are His bride, you will become what you believe and your tongue will speak it forth -  prophecy it, in other words, and you will create the you you believe you are. It doesn't matter what your circumstances look like - "for we walk by faith, not by sight". Will you believe what God says to you and about you? Not just in a vague, impersonal way. Oh sure -  God says to everyone his plans are to prosper them, he doesn't really mean me. He means my pastor up there or that rich family that comes to church every week in a Jaguar. 

This is another reason prophecy is vital to each one of us -  personal prophecy encourages, edifies and helps each one of us to believe.  He is interested and deeply cares for each one of us personally.  Who's report will you believe? Will you believe Satan's version of you or God's? Remember  - you completely become what you completely believe- you also partially become what you partially believe.  So go all in -  Love the Lord thy God with ALL your heart and believe Him with ALL your heart. Rich Mullins puts it like this  -

"I believe what I believe is what makes me what I am.

I did not make it, no it is making me,

It is the very truth of God and not the invention of any man"