The book is The War Of Art, by Steven Pressfield, not to be confused with The Art Of War, a completely (!) different book.
This small volume was recommended by an author/speaker at the Santa Barbara Writer's conference. One of the ridiculously successful authors at this year's conference mentioned that in his opinion The War Of Art was worth reading and rereading. I believe it was Mark Childress, though I could be mistaken.
My personal experience with books for writers is that the vast majority are not worth the time it takes to read them. I found The War Of Art to be the exception: it is a short, to-the-point description of how Mr. Pressfield thinks about and deals with the problem of inertia, writer's block, or what he personifies as "Resistance".
Without arguing that this book will be useful for everyone, I found Steven Pressfield's understanding of Resistance to be both insightful and useful in a practical way.
I'm adding it to my very short stack of books on writing that are worth paying attention to.