Struggling

I'm struggling yet again, doubting yet again.... How can you build up who you want to be when people keep bringing you down. Everyone says that you have to shrug it off and you have to be open to criticism well it's hard when you're already down in the dumps. I want so badly to breakaway from people who keep on underestimating me.  I swear.... I hate how people perceive me that way, I think somewhere in my crazy messed up mind it triggers something that keeps me there, where they want me to be.