There’s a lot in your thesis.
You created a record of what you did, how you did it and why that matters. Whatever the format or discipline, your thesis describes problems that you’ve solved or addressed.
You might share hints about obstacles that got in the way or ideas that you weren’t able to develop fully. There will be good stuff, tough stuff, simple stuff and difficult-t0-talk-about stuff.
There’s a lot going on under the surface of the many pages of your thesis. Reading it carefully ahead of your viva is essential for being ready to talk about your research with your examiners.