Why you lack confidence in your interviews

To succeed at a job interview is to show some level of confidence, whether in your skills or in yourself. Self confidence is not automatic; no one also comes into an interview 100 percent confident. However, most people show up regardless of their fear. So how can you be more confident in your interviews? 

1. Do your research ahead.
2. Prepare appropriately by practicing the things you have written down
3. Be confident in your skill and learn how to own them. It also helps to give instances where you have applied your skills in the past. Talking about your former success makes you more confident
4. Don’t be too in your head. What do we mean? Don’t be too conscious of how they perceive you or what you are doing wrong. If you are not clear with what their question means, it’s okay to ask, if you need to take a pause, do that. Just make sure to show why you are the best candidate for the job
5. Finally, relax. No one is chasing you. Have all the fun.

https://www.glassdoor.com/blog/8-ways-to-boost-your-confidence-minutes-before-your-interview/