In The Moment…
…it’s possible that you forget something.
…it’s possible you don’t understand something.
…it’s possible that you realise something.
…it’s possible that you think about something.
…it’s possible that you doubt yourself.
…it’s possible that you convince your examiner.
…it’s possible that you know something no-one else does.
…it’s possible that you’re the expert.
…it’s possible that you’ve made a mistake.
…it’s possible that you’ve got the answer to that unexpected question.
There’s a non-zero probability of all of the above. They can depend on a lot of things, but there’s a chance they all could happen, good or bad. Focus on some and you can find help, focus on others and you’ll only find distraction. You get to choose what you focus on, and what you do as a result.
Remember: it’s impossible to get to the viva without doing the work. You’re the reason you’ve got this far.