Steven Colbert recently interviewed the great storyteller Martin Scorsese about his new film Killers of the Flower Moon. The book the movie is based on is told from the perspective of the FBI. But when Scorsese was researching for the film, he heard the granddaughter of one of the characters talk about the love between her grandparents. It stopped him in his tracks.

“Where is the heart?” he and Leo DiCaprio asked each other. This wasn’t a movie about an FBI investigation, they realized, it was a complicated human story with love at the center. Their epiphany flipped the movie’s emotional center of gravity 180 degrees, and Scorsese had found a way to tell the story that he knew would be compelling.

Scorsese is a proven director. He could have made a great police procedural. But he knows that the real magic happens when his movies tell a story that connects emotionally with his audience.

So what does this have to do with start-up storytelling?

Standard startup advice—completely correctly—highlights the importance of Product Market Fit. Your company must make a product that your customers want. That they need. True.

But I’d like to expand that idea into something I’m calling Story Market Fit. If you can stop your audience in its tracks long enough to realize they need your product, they will be far more likely to move towards a purchase right then. If you can’t, your product gets lost in a sea of options and the decision gets put off, potentially forever.

If Product Market Fit means making the vitamin your customers need, then Story Market Fit is the packaging that makes your vitamins jump out from the crowded shelf.

Here’s how to shape your Story Market Fit:

1. Customer interactions are gold. Keep the target audience in mind. Every meeting, every phone call, every conversation at a conference is a place to listen for emotional needs and fascinating detail. I’ve worked with several companies trying to make autonomous driving safe. The description I heard in one of those conversations beautifully illustrates the challenges: Every time I think I’ve seen all the edge cases a car could face, suddenly there’s a woman running across the street chasing a duck with a broom. Keep a list of lively images and offhand comments. They give your story texture.

2. Fight sclerosis. In my day-to-day work, I keep a digital clipboard of sentences I can paste into my emails, but I find it’s valuable to frequently start from scratch. As you craft your story anew, focus on highlighting story elements that will resonate with a specific audience member or type of audience that you’re hoping to serve. Are they someone with a personal experience of the disease your new pharmaceutical aims to cure? Are they someone who is newly diagnosed or a long-time sufferer? Each type of audience will react differently to your story. Pay attention as you intuitively reach for more emotional language to describe your mission to a particular audience—it might become part of the story you should tell everyone.

3. Iterate. Like achieving Product Market Fit, achieving a Story Market Fit is an iterative process—and one that is never quite done, given the dynamic shifts of your company and your customers. As you grow, reach for new audiences, or introduce new products, you may need a new story.

4. Don’t breathe your own exhaust. Once we “know” what our customers need and what the key benefits of our product are, we often stop trying to learn more. We keep our certainty even as potential customers tell us about other ways they’ve solved the problem, or explained why they don’t need our solution, or asked for the one feature that they really need before buying. Your view of the world is rarely accurate, and certainly always up for debate and improvement. Keep listening.

Stories, all kinds of stories, are meant to touch us – not just our head but our emotions. I’m not asking you to go full Hallmark but reminding you that every one of your customers is a human (AI’s not quite there yet!) and every human has things they care about on an emotional level. Story Market Fit means inviting your customer on a journey to achieve what they’re looking for by purchasing what you’re selling.

If you’re stuck, like Scorsese, ask yourself: Where is the heart?