Writing is putting symbols to a page. Start in order to get over the hump of starting, continue past your own resistance, form a habit of paying attention to what you pay attention to, record your blind spots as well as your focal points. Transcribe someone else's words. Work a form. Substantially edit something. The original can't be harmed and if you already are closed, the worse that can happen is to remain closed. But you might open, or learn or play. Lower the stakes on your own game while bringing it up by keeping at it.