How can I look at this positively, but with caution?

So, something in my life is fixing to happen, fairly soon, you could say. It's going to be a pinnacle in my life, or at least that's how I feel about it. I'm extremely excited, but I do realize that I shouldn't get my hopes up, and I should be cautious to be too hopeful. I can't help it though, if it happens, this thing, I'll be on cloud 9, I'll be feeling wonderful and I'm literally counting down the days, but in the back of my mind, I'm trying to find all the negatives about what "could" happen and what "could" prevent it from happening. I just want to be balanced. I want to be able to be happy that this may happen, but I also want my brain to stop going into overdrive and be realistic about the fact that it "may" not work out the way I want. What's the best way to look at this positively? Keeping hope, but still being cautious?...