This is what writers do, they believe they can write and they do. That simple.
To all writers:
Please trust in yourselves, have faith in your voices, and tell the stories you want to tell.
Have confidence in your abilities, and keep going.
Remember that you can do this, that you can create your work, and that you are a writer.
Remember, success comes with the discipline to continue the work.
Pick up a pen, or sit at the keyboard, and write!