This technique for helping to write in quantity, Private Writing, was introduced in "IDEA HACKS!2.0". The method is to write down everything you think of, leaving nothing out. Its distinction lies in moving your hands and writing rather than thinking.
It is private, so in general you will write without intending to show it to anyone else. Because you don't worry about others seeing it, you can keep writing without stopping yourself.
These are the important rules of Private Writing.
[Important Rules] Don't show your writing to anyone else
(1) Allow for poor writing or trivial thoughts
(2) Don't stop writing
(3) Choose a time for writing
(4) Draw out your true, honest thoughts
(5) Develop your thinking beyond limitations
(6) If you get stuck, try changing your point of view
Like mentioned in the above entry, first choose a time and do your writing during that time. Set aside feelings of wanting people to like your writing, and just scribble down whatever comes to mind.
If you keep this up, eventually you will start smoothly writing text without pondering it over first.
Everyone has had the experience of words coming out smoothly in conversation even though they hadn't prepared beforehand. This is applying that to writing.