In an interview in The Bookseller, best-selling author Celia Ahern (P.S. I Love You) said she used to write through the night if she felt inspired. Becoming a mother changed the demands on her time.
She said, "I didn't think that anything creative could be done from 9am to 5pm to be perfectly honest. I didn't think you could force inspiration, but it actually works for me."
Now she keeps those hours Monday through Friday and she actually wroter her latest novel, One Hundred Names, more quickly than when she was on the more bohemian schedule.
Other writers have a different problem: they have a 9-to-5 job and feel unsure whether they can fit writing into the time left over. There are plenty of examples of successful authors who did that until they had enough success to go full time with their writing.
It suggests that our ability to be creative is much more flexible than we may think; it could be our attachment to romantic ideas about writing that holds us back.
If you'd like to change your writing routine, I have three tips:
1) Withhold judgment of the work you do on the new schedule. Give it at least three or four weeks before you go back to assess the writing. It's too easy to assume that a random bad patch is due to the schedule change.
2) Experiment. As you implement the new schedule notice what works and what doesn't. If getting up early to do a half-hour of writing doesn't work after you've given it a fair try, come up with a different alternative. It could be that staying up a half hour later, or devoting half of your lunch hour to writing, or putting in longer sessions on the weekends are more productive for you.
3) Make changes that support your new times. If you're going to get up a half hour earlier, for instance, also go to bed a half hour earlier. Otherwise sleep deprivation will kick in eventually. If you're planning to write for half of your lunch hour you may need to find a suitable place away from your desk, whether that's a nearby coffee shop or your company's conference room.
It's good to start with a positive attitude but even without one you may find that you are more flexible than you thought.
(If you want to find innovative methods for making the best use of your time, get my book, "Focus: use the power of targeted thinking to get more done. You can get it from Amazon or your other favorite bookseller.)