My late husband was an abusive, arrogant shit. He was, however, also brilliant. The single most valuable thing I learned from him was the importance of internal integrity. If you tell yourself your are going to do something, do it. No matter how small. If you tell yourself you are going to be a certain way, be it.
In fact, you can build up your self-confidence by making small promises and keeping them. And when you mess up, which you will from time to time -- forgive yourself. Don't pretend it didn't happen, or that you just changed your mind or weren't serious about whatever it was... Acknowledge that you messed up, and apologize--even if it's just to yourself.
My husband was terrible at it. He gave me the first part of the advice, but I figured out the second part on my own. He hated himself for his lack of integrity.
So, the best thing you can do for yourself is this:
- Keep your promises to yourself.
- Apologize when you mess up.
- Forgive yourself, and then go back to the first step.