J.A. Konrath is a mystery author and a funny dude. He also gives good writing tips:
Readers don’t want characters to be happy. They want them to be tortured for 90,000 words, and then happy at the very end. Maybe. That’s the essence of a page-turner.
If you don’t like plotting out a story before you write it, you can do it as you’re writing it. Just keep raising the stakes for your characters. Set up goals in the beginning, throw some obstacles in the way, and see if your characters sink or swim. And if your characters do swim, send a few sharks after them!