For some, writing is a passion. For professionals, it’s a job. When you invest your entire career in churning out words, your Muse devolves rather quickly from an inspiration into a math problem. Eventually, you come to take what you’ve written entirely for granted.

It’s all about the kind of output that a dismissive BBC documentary on the digital age recently dubbed “dead trees with information smeared on them” — long-forgotten words that carry my fingerprints and DNA.

Like two-legged offspring, they left home long ago to get on with their own lives … and they don’t call home very often.

Which is why an unexpected email has given me something special to chew on. The subject line: “A very late ‘thank you.’” It comes from Christine Cendagorta of Reno, Nevada, a byline of note in regional magazines and legal circles in the Southwest.

She writes: “After leaving teaching early on, I started (slowly) doing some writing for magazines. I saw your book in a writing magazine, ordered it and never looked back.” The book still has pride of place on her bookshelf, she says, as “a reminder of the good luck I had to find it and follow its advice.”

Not only that. In her final column for “The Writ,” the Washoe County Bar Association newsletter she edited, Christine actually includes a photo of “How you can make $20,000 a year writing (no matter where you live)” … 35 years after the first edition of my book on freelance writing was published.

Now, that’s a funny story. I’d been freelancing from Bismarck for several years when an old newspaper buddy, bemoaning the reporter’s life tethered to editor and desk, mentioned that he’d love to cut loose himself … “but, Nancy, that would never work for anyone but you.”

To this day, I’m not sure what he meant (or whether it was a compliment). But he got me to thinking: After departing two good positions to explore the world of freelance writing, I’d discovered enough by then to recognize that any decent writer with a shot of initiative could do rather well as an independent.

Throughout my years as a reporter and, briefly, a minion of state government, I’d always assured myself that I’d write my first book by the time I was 30. (I’d originally been thinking 21; it took me an extra decade to figure out that books don’t write themselves.)

I was 29 at the time, just six months in front of that looming deadline. At last I had something to write about. If I could freelance from my unlikely North Dakota ZIP code, I reasoned, the same principles might work pretty much anywhere.

But how does a wannabe learn to write an actual book, staring alone at her Selectric in a basement in Bismarck? Naturally, she looks for another book that’ll tell her how. I pulled several from the shelves of the Veterans Memorial Library and did just as their authors suggested — wrote a query letter and a detailed proposal, sent them off to the country’s biggest publisher of books geared toward writers (the same publisher, in fact, responsible for the instructions I was reading), and went on to other things.

Four months before my birthday, I was taking a peanut-butter-sandwich break in the kitchen when the phone rang. I grabbed it and found myself greeting the senior editor of Writer’s Digest Books … who was calling to offer me a contract. Me. An honest-to-God legitimate commercial publishing contract, with royalties and an advance and everything I’d dreamed of.

So, naturally, I turned her down. After all, that’s what my borrowed how-to-be-an-author manual said you were supposed to do: Always negotiate. Then — convinced I’d just converted the chance of a lifetime into one more amusing after-hours anecdote — I silently kicked myself … until she said, “OK, how about this?” and laid out better numbers.

Carol Cartaino was a wonderful editor. She helped shape my scattered basket of notions into a coherent manuscript by teasing out the thread that bound every topic: If you’re determined to take on a new challenge, get out there and give it a try. If you don’t already know how, find a book and take its advice.

Just like that Nevada writer who tells me she found the book — MY book — and took its advice — MY advice.

My editor and I had a few bumpy moments putting together “$20,000” and its second edition, which we raised to $25,000. (Inflation was big in those days.) I’d intended to call it “Freelancing in the Boonies.” She demurred, pointing out that A) the same advice born in the Great American Outback works equally well in major metro areas; and 2) writers want to make money. A lot of money.

I did manage to talk the editor and her marketing manager down from their first proposed title, which boasted of $50,000 a year. We Norwegians, after all, are a humble people.

I learned later that Carol was weighing two similar book proposals when she made that magical call to my kitchen. The other was from a very well-known author of books on writing and marketing who lives in New Jersey. His proposal referred to “the $100,000 freelancer.” She thought mine sounded more authentic. I do see that Robert Bly (the other how-to author, not the late Minnesota poet) has gone on to pen no fewer than 80 volumes of instructive advice since then. He describes himself on the Web as a self-made millionaire, so he probably wasn’t kidding.

In the long run, though, I give all the credit to my exotic ZIP code. As Sinatra crooned, if you can make it there, you can make it anywhere.

Those were the days, my friend, smearing information on dead trees without a thought of the pixel-driven world to come. Today most of the tools and anecdotes in my books are museum pieces, from my late, lamented Selectric typewriter to wise counsel on using Federal Express to speed slightly-over-deadline manuscripts from far afield to urban editors. Little more than a footnote now, old “$20,000” did pretty well back in its heyday, both in bookstores and the half-dozen book clubs that offered it as a selection. (If that term is unfamiliar, children, just picture Book of the Month Club and its kind as primitive precursors of Amazon, bringing best sellers to the boonies.)

The principle, though, still seems as fresh as spring. Tackling a new challenge? Get out there and give it a try. If you don’t know how to go about it, find a good book. You have my permission to trade dead trees for a download.