Start as you mean to go on. That means not feeling guilty when life -- or laziness -- gets in the way of writing. Tell yourself you are nurturing your idea -- giving it a chance to develop unimpeded by a corset of restricted time.
Do the dishes and think about your characters --talk to them as you scour the pots.
Mop the floor and visualise your heroine mopping floors or interrogating suspects or falling under the wheels of a milkfloat. How does it happen? What do you see? hear? feel?
Maybe you play out a scene that does not fit into your story outline. Write it anyway -- or at least dictate it to a recorder. Most computers nowadays allow you to record using a microphone.
So you have to learn how to do that?
That's what I call looping the string. You give yourself permission to stop the frenetic flurry of words you pound out to achieve an arbitrary word target. You allow yourself to learn a new technique, take up a new interest . Everything is grist to a writer's mill.
A how-to article on recording your voice on computer may sell to a writing ezine or on an article content site. Learn something useful and pass it on. Start publicising yourself as a writer.
Let one of your book characters follow the same learning curve --add another element to the novel in progress. Alternatively file the idea for a future book.
Always remember readers love to be entertained but they also love to learn something new in an entertaining fashion.
The more loops you have in your string, the more enticing your work becomes.
So never feel guilty about time out from writing. Some good will always come of it if you look in the right direction.