I read the same statement at Jennifer Weiner's site, where she said, "Here's a line that bears repeating: a writer writes." Luckily, she had a lot more to say and it wasn't the usual, "Be disciplined. Read a lot. Write a lot. Believe in yourself." Her advice is more specific than that.
She also said what I've been thinking for a while: it's not enough to just write and write and then consider yourself a writer just because you're writing. I think that getting published or getting paid to write is confirmation that someone is a writer. She stated it plainly:
If a tree falls in the forest and nobody hears, has it really fallen? If a writer writes poems and short stories and novels, but nobody ever reads them, is she really a writer? Nope. If you want to be a writer, you've got to bear the slings and arrows of outrageous fortune (not to mention evil reader reviews on amazon.com). You've got to put your stuff out there for the world to see, and fall in love with, or revile. In short, you've got to get published.
Actually, I've never read any of her books, and I'm not really interested in them, even though her writing style seems really good. Obviously I'm in the minority, since she's a bestselling author. She also seems to work really hard and cares about her readers, which is great. I'm sure I'm not the only person who'd love to achieve what she has, whether in writing or something else. She's found an enthusiastic audience for her work and she's been rewarded well for it. And, most importantly, she loves what she does and can make a living from it.