No matter the business, no matter the stage of the business, that’s the single most pressing question. I wish I’d understood that sooner.  (This article first appeared here on Inc.com.)

In our cool, hipster space here in Durham, North Carolina (we’re in a complex called the American Underground, which is part of a million square feet of old tobacco manufacturing buildings), I have the opportunity to bump into every sort of entrepreneur and would-be entrepreneur. We count 100-odd software companies within a half-mile of downtown Durham, and with that number, I don’t expect to go anywhere without bumping into somebody in my circle.

Last week, a peer investor of mine turned to me and asked, “What did you sell today?”

I loved it. Today, my Startup Factory investment fund sells to these constituents:

• Startup founders who will apply to be part of our program.
• Mentors who will volunteer their time to help these companies.
• Early-stage investors who will invest in these companies and help take them to the next level.
• Limited partners (our current and future investors in our fund).

I can’t be successful without the best of all of these groups coming together. So I take every opportunity to get in front of them and sell my company. Furthermore, we continually strategize on how to look for opportunities to get in front of these groups–especially the entrepreneurs, as without them the rest falls apart. Lately I have taken to the road to spread our message. (Need a speaker and a beer sponsor at your next meetup?)

Before founding The Startup Factory, I was a senior executive at seven companies over 20 years, and I draw upon those experiences every day as I advise the founders in our program. Despite the broad nature of the executive roles I held, there is one single, uber-dominant thread that rips through my soul every day.

At every one of these companies, I wished that I had put more firm-wide emphasis on sales. That emphasis includes both me personally and the sales and sales-support teams that reported to me.

Every company. It is a huge regret. What if I had sold more widgets?

You see, I am very much like most of you in that I love to plan, design, and build things. I wake up in the morning thinking about efficiency and disruption and speed to market. But none of that matters if you can’t sell something! Simple formula for start-ups is you run out of money eventually if you don’t generate revenue. You can only raise investment funds so many times.

So, whether you are like me and have to sell to start-up founders, investors, and mentors, or you are a current founder needing investors, employees, customers, partners, or just a friend, the question still holds.

What did you sell today?