Four words to remember.
They don’t mean that you’re ready. They don’t mean you’re perfect. They don’t mean that your viva will be easy.
They simply mean that you have got to this point in your PhD journey because of time, effort and talent. You did the work. Luck doesn’t hold sway over your progress. Your success is due to what you did.
Your success at the viva is built on a foundation of your work. A little more will help you be ready and that’s enough.
