Stuckish

The further I get in things, the more I realize how much I haven't thought through what's going to happen.  It's both scary and exciting.  Things can happen how they happen and that's fine.  But at the same time, I worry that the story might end up being too short/long/boring.  I've already hit a point where I'm really having to brain through what would happen with the characters and what implications that would have on how the story would unfold.  

I know where I want the story to end, but I wonder if it'll actually end up getting there.