When are you a writer?

I came across a thought in a book not too long ago, the character development book I'm reading (Yes, I'll put a link up to it here soon.) and there was a mention to it in a blog I read not long ago. When are you a writer? Is it like a job where you do it for eight hours before heading home and trying to ignore it the other sixteen hours or is it like being a parent where you just always are? Even if your child leaves home and never calls or writes, you still worry and wonder, you're still a parent. The book claims, and I mostly agree, that you are a writer any day you actually write. Even if you merely wrote a paragraph, a short article, or some backstory, if you wrote creatively that day you can call yourself a writer all day long. Why I don't fully agree with his statement is that sometimes taking a break from your story is good or life just interferes. That doesn't mean you didn't make the decision of what your character will wear in the next scene while stuck in traffic or came up with a great backstory while waiting in line at the bank or grocery store. You just didn't have time to write it down yet.
I think that being a writer needs to be a passion, not just a hobby or a job. It's something that is always percolating in the back of your mind, the wheels are always turning. Being a writer, at least a function one, this is probably true for nonfiction writers as well though that could theoretically be "just a job" to someone, is who a person is. It's how a person thinks, how they notice the world and maybe even how they respond to it. However, like every talent, the more you use it the better it becomes and the less you use it, the more you loose it. Just because you think like a writer most days does not mean you are one everyday if you never put pen to paper or hand to keyboard. So keep those words flowing and try to write daily.