Don’t trust myself to change job

I am feeling stuck and unchallenged with my current job. As much as I’d like to switch to a new job I don’t trust myself that I will be able to perform well if thrown into a new situation. I don’t have confidence in my ability to perform well as I have a lot of self-doubt and hence it affects my performance. I am getting by in my current job because I have been here a long time and it’s in my comfort zone. What can I do to get out of this situation?