When you read, you get the benefit of plumbing the depths of another's mind. When you write, you get the benefit of plumbing your own. And therein lies the great benefit to writing. The task is an exercise in self-discovery.
We all know reading should be a lifelong pursuit. In the same way, writing should also be a lifelong endeavor. They are both strategies for growth. You need both in your life. Start journaling. Start writing for your startup. Begin writing things you're passionate about. Just start and whatever you do, don't look back.