How important is mentorship for business owners? Incredibly, according to research. In fact, having a wise head with whom you can talk through the ups and downs of your business has been shown to double your chances of success.

“The success rate of mentored small businesses compared to those without a mentor is stunning: 70 percent of mentored businesses survive more than five years, double the rate for non-mentored small businesses over that same period,” reports my colleague John Rampton.

But getting all you can out of your mentor takes some serious relationship savvy. You need to know who to choose, how best to interact with them, and according to Wendy Torrance, the director of entrepreneurship at the Kauffman Foundation, what questions to ask.

In a fascinating recent article for the Wall Street Journal she shares stories of founding teams’ productive relationships with their mentors, relationships that have helped them win new customers and secure much needed funding. Getting these impressive results, she claims, is often down to an entrepreneur asking one single, incredibly potent question. What is it?

“What am I missing?”

"What am I missing?" might sound like a simple question — and it is — but Torrance insists it's also incredibly powerful. All entrepreneurs are inundated with more information and more variables than they can completely process. Balls get dropped, possibly productive avenues are left unexplored, and the forest is lost for the trees. Your mentor, with his or her experience and outside perspective, can help you spot when these oversights are hurting your business.

“The 'what's missing?' question can also give you a glimpse into things you should be anticipating in the future,” Torrance adds. “For example, when you're knee deep in product development, conversations with advisers about the big picture could get you thinking about your distribution strategy-and the accompanying staff needs-that will be essential to getting your product to market.”

“Because advisers are not bogged down in the day-to-day details of building or running the company, they can shed light on the bigger context to help the entrepreneur see the horizon, not just the hills and curves immediately in sight,” she concludes.

So next time you're lost in the fog of your day-to-day travails and in need of clear thinking, pick up the phone (or schedule a quick coffee) and ask your mentor “What am I missing?”