For the past 50 years, most agencies have been obsessed with the question 'How do we become more creative?' As an industry, we've got no shortage of great ideas. The problem is getting them out into the world without their dying or being compromised. It's frustrating how common a problem that is. So often we begin with world-changing thinking and end up making something we'd rather forget.

A few years ago, I worked at an agency here in New Zealand called ColensoBBDO. Between 2009 and 201 1, we won 21 Cannes Lions and 39 Effies – with a staff count of about 75 people. I had the good fortune of being part of an amazingly reliable creative machine that continually churned out brilliant creative product. Of course, we had amazing creative people, but it isn't just about great creative people. At Colenso, there was something else as well. And I think this was the reason why we managed to so consistently make great work happen.

We had this managing director, an Aussie guy called Brent Smart. Smarty's a brilliant leader for lots of reasons, but one thing that really stood out about him was a habit I'd never really seen in anyone I'd worked with before: he talked everybody up behind their backs. He'd constantly remind me of how brilliant the people were that we worked with. He'd enthuse to me that Steve Cochrane could come in on the hardest briefs that nobody could crack and when everything'd turned to shit, he'd just calmly turn out a D&AD-winning campaign.

He'd say the genius of Paul Courtney (our head of production) was that he never said no; he could figure out how to do anything. You could tell PC you needed a time machine and he'd just ask for a couple of days to figure it out.

And he'd talk clients up behind their backs, too. He'd say the brilliance of our Vodafone client was how he could manage anything upwards to get good work through. These weren't generic compliments. He didn't say, 'oh that person's such a nice guy' or whatever. He shone a light on specifically what was brilliant about each of us. And we were all flawed. You could pick any of us apart if you wanted to but Smarty chose to do the opposite. And it had a fascinating effect: everybody's belief in the people they worked with grew. Collectively, our confidence in what we were capable of became enormous.

We talk about advertising being a confidence game: many people need to have confidence – not only in the idea but also in the people who'll need to pull it off. Artistic creativity thrives on depression, alienation, low self-esteem. But commercial creativity's the opposite. It thrives on confidence and belief in each other. Just like we each have self-esteem as individuals, groups of people have a kind of group-esteem equivalent.

You see groups with low group-esteem. They have doubts about each other. They don't gel. They move forward tentatively. Their ability to stomach the uncertainty of creativity is very low. There are normal groups that get stuff done, believing in each other enough to achieve average things. And then there are those groups of people who consistently achieve great things. Like a great band, they all have absolute faith in each other. They delight in each others' brilliance. They have high group-esteem. And they do amazing things.

One sure way to create low group-esteem is to run around pointing out each other's flaws. It's such a common thing to feel frustrated by the shortcomings of others. To ease our frustrations by sharing them with someone who might understand. But doing this cultivates doubt. Erodes the confidence we may have been able to find in each other. Group-esteem is fragile. It's really easy to snuff out. But it's equally easy to build high group-esteem -just by doing what Smarty did.

We pass off whinging about each other's flaws as a kind of benign bitchiness. It isn't particularly attractive, but it doesn't really do any harm either. I think we need to start seeing this for the profoundly harmful thing that it is. Something that, in fact, sabotages our chances of achieving brilliant creativity. I think it should infuriate us when people behave in this way. Every bit as much as bad briefs and Link Tests and politics and the other things that stifle creativity. We should stop it. And the reward for doing so will be that our best creative ideas more consistently see the light of day.

I think that we should all cultivate Smarty's habit and see what difference it makes to the quality of creativity for the next 50 years.