Your examiners will want to talk about the strengths of your work in the viva. They’re there to talk to you about your contribution. Spend time in your prep thinking about what makes your work strong. How is it new? How does it make a difference? What makes it good? Why does it matter?
Your examiners might want to explore weaknesses. They might want to unpick clumsy sentences that don’t express what you had hoped. They may want to ask about limitations. The potential for improving on your research could be a rewarding topic of conversation. What could you do differently? Are you sure you’re right? Why?
Spend a little time thinking about your weaknesses. Spend much more time reflecting on your strengths. The background assumption for the viva is there is something valuable in what you’ve done – be ready to talk about your strengths!