Quote From Dalmation:
My VIVA is in less than two weeks, and yet I feel very depressed and blue about it. There are a lot of posts from people who describe feeling anxious and nervous, but not sad. I didn't expect to feel so down, and it's making it hard to focus.
I'd say this is completely natural as many people describe this feeling. Have a look at our website it may help: http://phd-viva.com/ It has a collection of experiences of PhD Vivas and gives advice and tips on the preparation for the viva.
All the best with your viva! :)