I don't remember when I first heard the expression "preparation is not production" but the failure to see the difference has been the most expensive writing mistake of my life.
It was a mistake that was chronic and mostly invisible. Even after I realized I was doing too much prep and not enough writing, I still found excuses - I actually accepted the myth that "90% of writing is procrastination". Little did I know I was under the control of a secret power...
'The secret power of idleness'
The preparation versus production distinction is not a new one. Here's Samuel Johnson in the 18th century.
"Some are always in a state of preparation, occupied in previous measures, forming plans, accumulating materials, and providing for the main affair. These are certainly under the secret power of idleness. Nothing is to be expected from the workman whose tools are for ever to be sought."
Research, note-taking, surfing the net, and reading-up on your topic are all essential. But they are not the same thing as production.
Yet these things can very easily come to replace writing. In my experience, it was not at all difficult to fall "under the secret power of idleness".
Only writing is writing
My advice to you is this: Remember that only finished products count. Planning is not writing. Watching documentaries is not writing. Cruising Facebook is not writing. Talking is not writing. Only writing is writing.
So, while it's true that your brain will want to choose whatever course of action that requires the least of its precious resources - the easy distraction - we simply have to find ways to get the writing done. It's a matter of nothing more than good old-fashioned discipline.
Writers, avoid the distractions
Johnson has more:
"I was once told by a great master, that no man ever excelled in painting, who was eminently curious about pencils and colors."
In our time the distractions are more numerous and compelling than colored pencils. And our distractions can go on indefinitely - for years - without our realizing it.
So, preparation is not production and taking this truth to heart may save you vast amounts of time and money.
In fact, you've just learned the most expensive lesson in writing.