“If I am I because I am I…
“If I am I because I am I, and you are you because you are you, then I am I and you are you. But, if I am I because you are you, and you are you because I am I, then I am not I and you are not you”. – R’Mendel of Kotzk
Simply stated, what that means can be summarized by
“Be yourself. Everyone else is taken.” – Oscar Wilde.
While that’s correct, let’s look a little deeper and ask why be you. If your life has a purpose (and it does) then you cannot find and fulfill that purpose without you being you. Your value is the unique you. There is no one else like you and therefore no one else can fulfill your purpose. Giving and sharing that unique you matters.
You are not just matter. It is you that matters.
“If I try to be like him, who will be like me?” — Yiddish Proverb
“If you want to be original just try being yourself, because G-d has never made two people exactly alike.” – Bernard Meltzer
Updated from the original sent 2/21/11
The Spinning Rabbi - Heart & Soul 
What if I don’t like who I’ve become? How do I change and become good?
Dear Bracha,
Firstly, I must remind you as it says on my home page, I’m not a real Rabbi.
It’s great that you’re asking that question. It means that you recognize that you don’t like who you presently are. That recognition is a very positive first step. It means that you know the difference between what’s good and that which is not.
“The entire purpose of our existence is to overcome our negative habits.” – Vilna Gaon
Since you know right from wrong, as the next step, develop a pause button that allows you a moment to always ask yourself if your next words or actions are good or not. That pause moment may seem like a long time at first but with repetition and practice it will become instinctual.
“Act the way you’d like to be and soon you’ll be the way you act.” – Leonard Cohen
You recognize that you don’t like who you’ve become because that’s not the true you and that’s what troubles you. The true and real you is embedded in your soul. It knows what is good and what your true purpose and mission is.
There are many posts on this site that will give you some more tips on staying on the path you truly wish to be on.
Perhaps speak to a real Rabbi for some next steps. I personally would recommend your local Chabad Rabbi.
Thank you for asking me your question!