Startup founders are chronically “just too busy” for exercise, friends, family and certainly hobbies. A single-minded focus naturally seems sensible but, counterintuitive though it may be, extracurricular activities have important indirect benefits for building a business.

A study released last year found that STEM -- science, technology, engineering and math -- graduates who had a creative outlet growing up, such as music, woodworking, painting, or even magic, earned more patents and started more businesses. Business owners self-reported they considered their hobbies “often important” in problem solving, while 58 percent  said a creative outlet “definitely mattered” in their careers.

Related: 10 Myths About Creativity You Need to Stop Believing Now

People increasingly realize creative pursuits improve brain function. Still, as a society, we overestimate the benefits of working overtime at the expense of creative expression and leisure.

The “keeping our nose to the grindstone” attitude stems from the antiquated idea our brain has two sides, one for analyzing and the other for innovation. Now we know that although our brain is physically separated, the two sides interact constantly. Children classified as “gifted” mathematicians have brains with opposing sides interacting stronger than other students.

The aforementioned STEM study showed this is true in the classroom and the real world. STEM graduates with a strong analytical brain develop their creative brain in tandem.

Many famously successful people have broad interests. Bill Gates' many interests range from virology, oceanography to  fertiliser. Einstein played the violin. Gauguin, the revolutionary French painter, started his own political magazine while living in Tahiti. Before starting Apple, Steve Jobs educated himself on type fonts after deciding to take calligraphy lessons.

Whether you consider these successful people "eccentric" or “Renaissance men,”  they were exploring interests outside their key discipline while succeeding within it.

Related: What Does the 'Creativity Crisis' Mean for Innovation?

The STEM team described the importance of the “knowledge economy,” in which information is traded as if it were a physical product. They argued this economy will require people with broad skills. There’s no doubt that the knowledge economy will rely on innovation and a hybrid of talents. Building a repertoire of skills will help you notice trends and solutions across different disciplines.

Busuu, the language-learning social network, needs innovative and creative human capital to compete with fast-moving competitors like DuoLingo and Coursera. Their staff must show an interest in languages. Think that sounds over-zealous? If the job is Mobile UI Designer in London, surely English is the only necessary language to know.

At Busuu, breakthroughs come from a set of coincidences. A Spanish-speaking developer learning Japanese could notice that, unlike Spanish, the personal pronouns in Japanese are quite difficult to pick up right away. Implementing a Japanese lesson on personal pronouns later in the course could be the necessary touch to make Busuu a front-runner.

Knowing your craft is good. Knowing your craft plus a few others is great. Thinking outside of the box creatively, everyday, is a fundamental part of working in the Knowledge Economy. That requires boosting the interaction between the left and right sides of the brain. Achieving that isn’t easy -- no one said learning an instrument or language is -- but it contributes to the vital connections needed to foster successful, innovative businesses. Even for people too busy to believe it.

Related: This Simple Habit Could Be the Secret to Increasing Creativity