You don't write because you want to say something; you write because you've got something to say.
Writing is simple. First you have to make sure you have plenty of paper... sharp pencils... typewriter ribbon. Then put your belly up to your desk... roll a sheet of paper into the typewriter... and stare at it until beads of blood appear on your forehead.
Mostly, we authors must repeat ourselves -- that's the truth. We have two or three great moving experiences in our lives -- experiences so great and moving that it doesn't seem at the time that anyone else has been so caught up and pounded and dazzled and astonished and beaten and broken and rescued and illuminated and rewarded and humbled in just that way ever before.