The Nonfiction Writer's Wish

I'm just about 2/3 done with my second book. Which feels like progress. And it is. But I'm finding this last 1/3 to be much harder to write than the first 1/3. And while my first book was chronological, this one is not, so it's more challenging to make sure I'm pulling in everything. Finalizing order is a whole different topic, but I won't worry about that until all the content is written. Or maybe that's my problem. That I don't at this point even know the order of things. Either way, the thing I keep saying to myself is this: I wish I could write fiction. Fiction is the ticket. Fiction is so the ticket. But try as I might, my brain doesn't think that way. Dammit.