We spend SO much time thinking about writing, planning to write, dreaming about writing, wishing we could write, making lists for writing, taking notes for writing. See a pattern here? Why do we hesitate? Because we're terrified. We're terrified it won't be any good. This is silly.
OF COURSE IT WON'T BE ANY GOOD! Have you ever seen a first draft of Cormac McCarthy or Michael Chabon? Do you really think Sherman Alexie jots down the first thing that comes to mind each morning on a Krispy Kreme napkin and hands it off to his publisher? Dylan Thomas' "Fern Hill" is one of my favorite poems; he wrote over 200 drafts before he completed it.
Anne Lamott devotes an entire chapter in Bird by Bird to Shitty First Drafts. You should read it. Thinking that you should automatically be a great writer because you know how to type is about as dumb as thinking you should be a Olympic medalist because you know how to run or swim. So it won't be perfect. You gotta start somewhere. Write it down; don't worry about writing it right.
Relax. Have fun with it! Go a little crazy - cause NO ONE IS GOING TO SEE IT. There's nothing more satisfying than unleashing your creativity. Don't sit down to write a book. And don't write about the boring day you had yesterday. Just write down a funny or weird story someone else told you once (it's easier to start with something not-so-personal) and change it up a little bit. Make it your own by tweaking the events and inventing dialogue and creating a character to whom the story happens.
Do it today. No excuses, anyone can spare half an hour. Okay, do it this week, or in the next two weeks, I can wait. And let me know how it goes.