With that being said Eddie Izzard, with little training, ran 43 marathons in 51 days. He didn't break any records or win any medals, which I suppose is roughly analogous to getting a book published, but he did do it, over and over again, which is arguably writing the damn book.
All of this suggests that I could probably run a marathon right now if I really felt like it. Fortunately (I'll say it again) I can't be arsed. Same goes for writing the book, because nothing inspires me enough to write an entire book. But I could do it, because I've absolutely written a book's worth of words over the past few years.