I seem to be differing somewhat from what other people are saying in advice about staying positive, and that may be because my experience getting through this is as being diagnosed with stage II, which, let's face it, carries less scary stats with it (though I still found them pletny scary especially given that I had risk factors like perineural invasion).

So, anyway, I hesitate to say this but I will. Its about what worked for me, there may be other advice that is more suited towards what will work for you.

Speaking strictly for my experience, I needed to get through a couple of times of "meltdown" which included a lot of fear and despair in order to really reach total warrior mode in fighting my cancer. I'm glad I didn't try to numb those moments out too much with sedatives or pain killers because once I got through those I realized that despite all that, the one choice I had was to fight or not to fight and given that one choice, fighting was the only option I'd be happy with later. And I mean "later" as in if the worst case happened.

Of course if you can't seem to pull yourself out of despair for days on end the it's time for medication to help you with that. Depression can be crippling in fighting the good fight. But sometimes, going to that darkplace a little can be helpful in forming resolve.