boxing mental help

What is a good way to increase my confidence when I spar or box?Because I heard that mental focus is a huge factor when It comes to boxing.I'm always getting put down and bullied for something I can't really control,how do I get passed that and become a better fighter. Train hard have no fear and tell your self no one can beat me when I enter the ring if your beat up find what mistakes you made and train harder look at styles and in your mind look to see how you can beat that style p