One of my favourite questions to ask final year PhD researchers is “What’s the biggest challenge in the way of you finishing?”
It’s good to focus. It’s good, even if it is something scary, to get it out in the open. Once it is acknowledged, it can be worked on. Once you’ve said, “This is the biggest, most important thing I still have to do,” then you can start to plan what actions need to be taken. Maybe you won’t work on it every day, but you know what your biggest priority is.
It could also be a good way to frame your viva preparation.
Maybe, “What is the most important thing I need to do before the viva?”
Or, “What is the biggest gap in my preparation?”
Or, maybe try asking yourself, “What’s the best thing I can do to continue my success?”