Like many novelists, the sci-fi writer Neil Gaiman rarely does a public reading without being asked the tiresome question: "Where do you get your ideas?" He used to respond facetiously - "From a little ideas shop in Bognor Regis" - but that grew boring. "I make them up," he says now. "Out of my head." People don't like that. "They look unhappy, as if I'm trying to slip a fast one past them," Gaiman writes. But the truth, he admits, is that he doesn't know where his ideas come from.

Through history, creative people have said the same, but that hasn't staunched the deluge of pop psychology books on how to generate ideas. The surprising problem with some of them is they are amazingly boring; How To Have Creative Ideas, by Edward de Bono, may contain useful advice, but, as with his other work, I've never had the perseverance to find out. (Hilariously, he once wrote a book called How You Can Be More Interesting.) More often, they're plagued by a familiar, soul-destroying "zaniness" of the kind that inspires those team-building awaydays where managers play paintball and try not to ponder the futility of existence. One such is Doug Hall's book Jump Start Your Brain: A Proven Method For Increasing Creativity By Up To 500%. Hall runs workshops using the Eureka!® Stimulus Response™ method, so next time you have a eureka moment, best ask his permission.

It's tempting, amid this nonsense, to conclude that creativity is intrinsically mysterious and can't be elucidated. But what if we're just approaching it wrongly? "Blue-sky thinking", like its cousin "outside the box", has been mocked into obsolescence, but the metaphor they embody persists. We think of creativity as unrestrained and wild - that if we take the lids off our imaginations, great ideas will bubble up. (There are at least three books called Unleash Your Creativity.) But the counter-argument, increasingly influential in business, is that creativity thrives on constraint.

"Is there something in the nature of constraints that brings out the best creativity?" wonders Scott Berkun, whose absorbing essays on innovation are at scottberkun.com. Consider a good haiku or sonnet, and the answer is obviously yes: it's precisely the limits of the form that inspire new ways of working inside them. In the workplace, that means no more open-ended brainstorming: if you want the best answers to a question, focus it narrowly; consider a time limit, too. Google sometimes puts fewer engineers on a problem than it needs; it inspires ingenuity.

The blue-sky metaphor further implies that ideas come from nowhere. But every idea is a combination of others, Berkun notes. "Say it five times... Every amazing creative thing you've ever seen [can] be broken down into smaller ideas that existed before. An automobile? An engine plus wheels. A telephone? Electricity plus sound... If you want to be a creator instead of a mere consumer, you must see ideas currently in the world as... ingredients waiting for reuse."

So the pressure's off. You don't have to launch yourself into blue sky, nor conjure ideas from thin air. In fact, you won't succeed if you try.

oliver.burkeman@theguardian.com