Be a sadist. No matter how sweet and innocent your leading characters, make awful things happen to them -- in order that the reader may see what they are made of." [From the preface.]
Reading a novel, War and Peace for example, is no Catnap. Because a novel is so long, reading one is like being married forever to somebody nobody knows or cares about.
Write to please just one person. If you open a window and make love to the world, so to speak, your story will get pneumonia.