Bot you and I know that it is really hard to change bad habits. But maybe this little tidbit of scientific fact can help you. It is of course possible to change who you are, and that should be something comforting because that means that you can strive to evolve without endangering yourself, since, there is no self.
We’re talking about neuroplasticity, our brains power to change, not only mentally. I would like to call it the effect of realizing that you and what constitutes your self is not set in stone. Also called perspective, hah! Well, the point is that you can change both mentally and physically, even in your brain.
Check out my this post from when I was meditating for a whole week (I just read it and it is ridden with spelling errors.. but hey I wrote all of that on my smartphone with a cracked screen).
Or check out this article where they talk a bit more about the plasticity.