My advice to you anon is the next time you have a free morning, or afternoon, get on your computer. The only way to break habits is to simply break them. It sounds like you have caged yourself into a forced writers block. Don’t get me wrong, some people need schedules. We live busy and full lives, sometimes you have to schedule yourself and say no matter what I’m writing at that time.
But, you also must be able to write whenever possible. If you find yourself with a few hours off, you have to be able to write. No matter time.
I don’t have this problem and I had a hard time finding tips on this specific problem on the internet. But perhaps these tips on finding and making the time to write will be of some assistance.
Writer’s Digest: Finding the time to write.
About.com: Finding Writing Time
Writing: Find the time or Don’t.
How to Find, Rather Than Make Writing Time
Writing World: Finding the Time to Write
Five Tips for Finding Writing Time