School Anxiety

I am working on a doctorate degree. I have the habit of dreading my work and fearing failure and humiliation. I feel the urge to quit school as I am doing assignments and writing papers. I believe if I can develop a new thought, practice it enough, I can enjoy school and my life more. What questions can I ask myself to help clear my habitual worrying? I know I am capable of doing well in school, but I want to worry less.