If you’re doing a PhD, the viva is coming. It will happen. It is all about your work, your ideas and what they all mean. The viva reveals things, to your examiners and to you. Your examiners have read your thesis and are exploring something new to them; they’re exploring it with you, the researcher who did it.
However you feel now, today, there’s time to get ready. If your viva is two years away, you have time to explore good examiners. If your viva is tomorrow, you have time to make quick summaries or use questions to unpick your argument. If your submission is six months away you have time to review your thesis structure and explore if there’s any way to improve it. If you submitted a month ago, have time to carefully read your thesis.
Doing a PhD? Your viva is inevitable. But you can be ready when you reach that day. You have time.