There are many strains of the dreaded Writer's Block, but typically it comes down to: what do I write next?
Now, some writers will want to "feel out" the direction -- and I do that, too! For a couple pages or so. But after a certain point, you might feel silly or delusional -- like running on a treadmill and telling yourself you're actually getting to your destination.
I'm all for letting your characters guide you (rather than having the story guide them like pieces on a chessboard). I'm all for creating original, surprising structures. And I'm all for writing exercises and playing around the character, dialogue, pacing, whatever.
But I'm also for clear planning. Setting goals. Not wasting time.
So I'm a huge fan of outlining. Here's a little vid that explains my index card love in some more detail...