Everyday we are so busy that we cannot think of a time to really stop and have time to create, unless it is your job. I have been trying to write a book for the longest time, and I really have a hard time getting it done. It is not that I don't want to, but obstacles get in the way. There me be times where inspiration only comes in spurts, but what I have learned from just basic research, is that others encourage the idea that you should write even when you feel like you have nothing to say. You can always go back and fix it, but the idea is to get something written. It helps progress the process. Even if your thoughts are at a zero level, you can go jot down on a piece of paper " I have no idea what I am doing. I cannot write. My mind is blank. I had cereal for breakfast" and whatever else comes to your mind. You write without a filter.
What we can do is try to fit in 10 minutes a day at the least.
Besides that, at some point (if you're lucky) you will possibly have some spare time to travel and be able to have some time to yourself where you can finally write your book. Usually authors tend to get inspired of the location they go to, to base their story in because they will have real events and places to compare it to.
So, please utilize your time to relax but allow it as a time in which you allow yourself to grow spiritually and creatively.
As I like to say for all my hopes in dreams, "Inspire and be inspired."
Good luck and write that best seller you have always dreamed of.