Steve Blank is best-known for being the creator of "The Lean Startup," a movement that became popular after the dot-com bust of 2000 and continues to be widely practiced today. Its tenets, such as iterating fast and following what your customers tell you rather than your long-term plans, grew out of his thinking and writing on customer development. Blank previously had started or been involved with eight upstart companies in Silicon Valley, so he'd absorbed more than a few lessons about how scrappy endeavors struggle or grow. In 1999, he "retired" and moved into writing and teaching about startups. But while he's built up considerable renown as a startup expert over the years, his philosophies would not have fully formed without some harsh words from a superior early in his career. --As told to Christine Lagorio-Chafkin

I was a do-no-wrong young marketing executive with the title of VP of marketing when I got some advice delivered with a two-by-four to the side of the head. And it became the basis for what eventually became the Lean Startup movement decades later.

I must have been late 20s, early 30s, and there were like 10 of us that were building a fairly complicated thing at the time called a supercomputer. The company was called Ardent. There were people at the company who actually knew what they were doing, all senior execs. We were having what was called a system-planning meeting, thinking about what features we should build into the machine. The engineers were talking about what kind of graphics this thing should have, and I was sitting there thinking, "I vaguely understand what they are talking about." I had recently worked with Pixar. But the most dangerous thing in the world for a marketeer is to sit there thinking, "Hey, I haven't heard the sound of my own voice in a while."

I decided to pipe up and said, "Well, I think we need the most sophisticated, sum of all graphics features," and rattled on about it. The CEO, Alan Michaels, turned to me. This is a guy whose personality is like Elon Musk combined with Steve Jobs. He turned to me and in the quietest voice he said, "Can you repeat that again?"

So I did--thinking he actually was soliciting my input, I sort of went off with more features and my opinion. Then he put his face about six inches from mine, literally right out of a Marine boot camp, and started screaming at me.

He said the following: "There are people in this room who actually have been in this industry, know these customers, and know what the hell they are talking about. You are a disgrace to the profession of marketing."

I felt like I was six inches tall. Until he said the next thing, and then I felt about one inch tall. He said, "Get the hell out of my building."

I thought I had just been fired. And then he says: "And don't return until you really know what customers really need and want. And then you will deserve the title of VP of marketing. Until then, you don't have it." I could have crawled out of that conference room, maybe underneath the doorframe.

At the time, I of course didn't appreciate the yelling, but I've learned over time that the smarter the person you are dealing with and the larger the ego, sometimes the message has to be delivered with more than a memo. If it had been just a memo, I wouldn't have heard it. That's why I say it was a two-by-four to the head: It truly forced me to change how I thought about my behavior. And the role of marketing in a startup.

It gave me the impetus to go out and tour the country with the VP of sales. We met with one of the co-inventors of the IBM 360. We went to Brown University and Boeing and met the people building computational fluid dynamics. We went to Los Angeles and met the people doing space shuttle engine design. Basically all over the country, meeting people who would use our computer. And when I walked back in 90 days later, I could say, here's the archetype for our customers and here are the features they want and here's why they want them.

That changed my entire career as a marketeer. Don't open your mouth until you understand what customers need or want--or else you are just adding hot air to the conversation. That became the basis for customer discovery, which is a key component to the Lean Startup. It has probably changed the lives of hundreds of thousands of people over the years.