The War of Art by Steven Pressfield. This is the book I've recommended more than any other, and have been thanked by people I've recommended it to disproportion

The War of Art by Steven Pressfield. This is the book I've recommended more than any other, and have been thanked by people I've recommended it to disproportionately. He's got a few other books--Do The Work, Turning Pro--that cover similar ground, but The War of Art is the best of them by far.