My absolute favorite book on writing is Becoming a Writer, by Dorothea Brand. It isn’t about the technical aspects of writing. Instead, it tackles the stuff that blocks people from writing in the first place. It’s a really nice read, too. I picked up the audiobook version, and I find it very soothing and pleasant to listen to, in addition to being super helpful. Her style is just really charming.
Brand wrote her book on writing quite a while ago; she actually talks about picking the perfect typewriter, but everything else in there is still pretty relevant to the average writer. This is the book a lot of writers are really searching for when they go through all sorts of other sources looking for inspiration. She isn’t there to help you polish your sentences, or figure out how to define chapters, but she breaks down what really stops people from just getting in front of a blank page and making progress, and offers practical solutions and encouragement.
I first heard about her on Chris Brecheen’s blog, Writing About Writing. Which is also a great source for encouragement, and a well placed kick in the butt, when you’re stuck. I’d suggest this book as a good first, second, or last resort for someone who wants to write but is feeling discouraged and frustrated.