I'd say that the better you prepare for the fast, the easier it's going to get. Since you're starting today just be sure that this is what you want. Find all sorts of reasons why you want to fast and really make sure you have a firm grip on them; they are going to get slippery. As long as you go into this knowing that you are about to do battle with an enemy that knows all your tricks you'll be fine.
Don't let yourself think too much about how long the fast is and what you'll eat when it's over. Just accept the moment and let the fast be the way it is.
I wish you all the best and keep us updated on your progress!