When I became president of West Elm, the company had a narrow design vision. It was like that Henry Ford quote: "Any cus­tomer can have a car painted any color that he wants--so long as it is black." Our mission was about having customers buy our style, not about reflecting theirs.

That had to change. It was my job to reinvigorate the company, and I saw so much opportunity in the expanding aesthetic of  home design. Customers wanted more autonomy in their style choices, and the ability to order cars (or their equivalents) in any color of the rainbow. Instead of proclaiming ourselves the style authority, we had to give up that power--in practice and, crucially, in writing. Our resulting guiding statement promises that West Elm "inspires you to express your personal style at home."

It seems simple, but such statements go far beyond marketing. Whether you are redefining your business or launching one, distilling your hopes and dreams and plans into an internal slogan is a challenging but necessary exercise. If you succeed, your guiding statement will act as a built-in editing device and focus your future decision-making processes.

One of the biggest mistakes I see companies make is writing a statement for the way the words look on paper, with little regard for how they will be expressed in action. When my company updated our words, we also updated our practices, with changes that had to filter right down to each sales associate in every store. For example, we stressed the importance of personal communication, and did away with rote retail greetings like "How can I help you?" This was not difficult, because when we began carrying collections from local artisans, customers recognized the makers or the neighborhoods where the products were made, which prompted more natural conversation. We also put more of an emphasis on regional communities, primarily through ground-level store events and social media. That helped us become better listeners about what customers really want, and guided us as we expanded product offerings and created a new, more eclectic, modern look. And it led us into the world of handcraft; three years after launching our local initiative, this shift to artisanal products has redefined our company.

Figuring out what your words should be isn't always easy. The founders of  Public Supply, a Brooklyn-based maker of office and writing supplies, spent more than two years hashing out what their company valued and how to express it. "It was important that our mission statement reflect group thought," says co-founder W. Brian Smith. "We'd have long chats over drinks, or our internal meetings might involve debates about who we are and what we're doing." The for-profit company, which sells products through West Elm, donates 25 percent of its revenue to public-school arts projects.

After many a group brainstorming session, Brian and his partners wrote down Public Supply's mission--"We create writing essentials in support of public-school arts"--but they didn't consider their job finished. "We regularly review our mission statement," says Brian. "When we update the website, for example, we ask ourselves, is this how we're currently thinking and acting? We want to make sure that our words and strategies truly reflect how we feel about our business."

This is exactly how modern businesses must define their identity: You have to be flexible and open-minded when it comes to revising or revisiting what you originally set out to do. That makes for a stronger guiding statement and a more thoughtful strategy, which then adds up to a sustainable business.

From the June 2016 issue of Inc. magazine