Just as a samurai wouldn’t charge into battle with a rusty sword, a writer shouldn’t leap into writing without sharpening his skill.
Yes, writing is a skill. It’s a craft that can be learned and developed with practice.
This also means it can be lost like any other skill. If the writer isn’t flexing those creative muscles, they atrophy.
Show of hands: how many of you took a foreign language in high school, then hardly remember a word four years later? (Yes, of course I can see you. I’m an IT guy and I’ve hijacked your webcam. Jim B in Philly, get that finger out of your nose.) That’s exactly the kind of thing I’m talking about.
This is why writers hide in their offices for hours at a time. This is why we are voracious readers. This is why we study the craft, and why we have to keep punching those keys. We keep our swords sharp by polishing them daily, because we don’t know when that next anthology invitation or three-novel contract will land on our desks. We need to attack those opportunities with vigor, and if we’re not ready, we may not see another opportunity like them.
Create every day. Can’t get going on that short story or novel? Write vignettes. Write a few sentences of dialog. Write a piece of flash fiction. Can’t get to the keyboard? Carry a notebook and scribble in it, or punch something into Evernote on your smartphone. Scribble a mindmap on a napkin at dinner. Free associate with a friend.
Whatever your ultimate method, hone your sword. Be ready for those opportunities.