Self-doubt
Worries
are possible worse case scenarios which usually never come true. It's a protective mechanism of your brain to keep you from danger. Worries are not real.
Overthinking
Thoughts and emotions are not you. They are visitors - when they come, have a good chat, treat them and yourself with a snack and then say good bye.
Repetition
If you repeat something often enough, you will believe it. Whether it is true or not.
Fear of failure
If you fear something, you really fear what it means about you. Get clear about the meaning to clear the fear.
Self-image
How you see yourself sets the blueprint of your life. Unless you change it, there is nothing new to build upon. You tolerate what you think you deserve.