Teenage Daughter "Issues"

My daughter and I have always been close, but definitely butt heads about my expectations of her attitude and behavior towards me and her Dad.

She’s a really good kid–smart & loving, but she gets so bogged down in negativity about how things will turn out, who doesn’t like her, why she can’t do something well, etc, etc. I try to help her look at her thoughts vs circumstance, positive spins on situations and she just gets angry and ends up being disrespectful. It’s as if she enjoys being negative. I would normally just let a person like that be “who they are”, but I am still responsible for her and hate to see her do this to herself. How can I best help her?