Getting good story ideas can be hard. Sometimes all you need is a creative boost. For me personally, I get my story ideas when the "creative well" is full AND I'm doing something boring (like trying to fall asleep, doing dishes, folding laundry, or waiting in line). So I have to make sure my creative well is always full to take advantage of the boring parts of my life.
Literary Agent Rachelle Gardner always gives good advice. She has a list of things you can do (when you're not writing) that will feed your book-writing later in her post: How to Become a Better Writer.
Routines for Writers is a great resource for any writer. Shonna Slayton has multiple posts on boosting creativity, including this one on Daydreaming. She gives a few methods to get the creative side warmed up.
Have you ever heard of the Rule of Twenty? Upstart Crow writes that your first 5 or 10 ideas may not be gold, but keeping trying.Creative riches lie ahead!