The hardest part of writing a novel is knowing where you're going but not exactly how to get there, and waiting until inspiration lifts the fog of war from that part of the terrain.
Some believe in plowing ahead and just writing their way through it on the theory they can go back and fix it in rewrites, but I don't want to have to rewrite an entire novel when I could just try to get it right the first time.
Half of the job of being a writer is sipping coffee and staring moodily into space as you try to figure out how to solve problems you created for yourself.