Read Becoming a Writer by Dorothea Brande. Then do what it says, including the tasks you think are impossible. You will particularly hate the advice to write first thing in the morning, but if you can manage it, it might well be the best thing you ever do for yourself. This book is about becoming a writer from the inside out. Many later advice manuals derive from it. You don't ยญreally need any others, though if you want to boost your confidence, "how to" books seldom do any harm. You can kick-start a whole book with some little writing exercise.
Hilary MantelMy first career ambitions involved turning into a boy; I intended to be either a railway guard or a knight errant.
Hilary MantelI spend a lot of my time talking to the dead, but since I get paid for it, no one thinks I'm mad.
Hilary MantelSuppose within each book there is another book, and within every letter on every page another volume constantly unfolding; but these volumes take no space on the desk. Suppose knowledge could be reduced to a quintessence, held within a picture, a sign, held within a place which is no place. Suppose the human skull were to become capacious, spaces opening inside it, humming chambers like beehives.
Hilary Mantel