Ask your family and friends to give you a little space, time and quiet in advance of your viva. You need a good environment to prepare in. They can help provide that for you. Let them know what you need and work with them to make it a reality.
Ask someone to drive you to university on the day of your viva, if you’re having your viva in-person. You need to arrive rested. Travelling by public transport or driving yourself could take away from your focus and energy; asking for a lift could help you to arrive at your viva in a great condition.
Ask yourself to believe something: to believe that you are good enough. To believe that you have come as far as you have through hard work, personal development and making something that matters.
The last favour might be the biggest you could ask, depending on how you’re feeling – but if you can grant the request you’ll find a confidence that will help a lot on viva day.