It’s Friday afternoon in the Red Carpet lounge of Chicago’s O’Hare International Airport where I have an easy connection en route home from working with a client in Michigan. I check my phone and find an email from the business development person at an ad agency I know of but have never worked with. Her firm is looking to hire a consultant and from the email she’s clearly enjoying the power she’s been given to solicit proposals from multiple sources.

“Today is your LUCKY DAY!” she begins. Sigh. “We’re looking to hire a consultant and your name is on the list of people we’re inviting to submit proposals!!”

Buried in an email full of flowery colloquialisms, exclamation marks and liberal use of all-caps type is a laundry list of self-prescribed solutions that she’s looking for a consultant to deliver. She completes the email by asking me to fill out a questionnaire she’s attached. Without opening the attachment I type my reply. “Thank you for thinking of me. I have numerous articles published on my website on the issues you identify. The appropriate next step would be to read through them and determine for yourself if I’m the right consultant for your firm. After that, if you do see a fit, let’s schedule a call with the owner of the firm.”

I sign off certain that she won’t do her homework and that I’ll never hear from her again. Then I forward the thread to a friend who works in the same field, with a note, “Another one for the book. Hello from O’Hare.”

David is a competitor, a collaborator and my regular trading partner in war stories. “The book” is the collection of such stories we joke about publishing one day. Less than a minute later my phone is ringing. He too is connecting in O’Hare, but he’s in the Admiral Club in another terminal, which might as well be in another city. “I got the same email,” he says. “I just sent you my response. Safe travels.”

Instead of replying, he has forwarded the email to the woman’s boss, the owner of the firm, with the briefest note. “This woman is incompetent. Fire her.”

I laugh out loud. In our friendly, ongoing game of one-upmanship he’s beaten me again. Later, the firm’s owner does indeed take David’s advice, lets his employee go, and hires the consultant who suggested he do so.

Confidence and expertise are inextricably linked, not like two boxes connected in a PowerPoint flowchart, but more like two areas of the brain connected through a complex overlapping network of neurons. Expertise builds confidence. Confidence communicates expertise. Expertise without confidence, it could be argued, is not expertise at all, as the aim of a transaction of expertise is to give the client the strength to move forward. It’s difficult for one human being to give strength to another if that first person is not herself strong or behaving like she is.

I was wrapping up a seminar in Sydney, Australia once, fielding the final questions of the day. The last one came from a woman who summed up the importance and difficulty of confidence. “This has been great,” Lynn (not her real name) said. “Now I know what to do.” She paused. “But my question is, how do I grow the balls to actually do it?”

The room broke into laughter at her direct language but this was and remains the million dollar question. From where do you derive the confidence to take bold action? What was it about David, and to a lesser extent, me, that caused us to reply in the confident manners we did? We both recognized an uninformed, unsophisticated buyer wielding a flawed process. We both refused to validate her methods by agreeing to her requests. Neither of us accepted the vendor position in the relationship nor did we over-invest in the sale. We each, in our own ways, suggested alternative paths forward. What would others have done? Would Lynn have replied this way or would she have completed the questionnaire and waited for the next step to be dictated to her? Why could David easily do what Lynn and many others struggle to do?

David himself offers an explanation. Somewhere in time between O’Hare and Sydney, he calls. This time I’m at my desk and he’s driving through a snowstorm in Nebraska on his way to a client. We trade emails most days but impromptu phone calls are rare. This must be big. I can hear the excitement in his voice. “Where does confidence come from?” he asks over the sound of windshield wipers.

“Sorry?” I reply. The question doesn’t match his tone. He sounds like he’s solved Fermat’s Last Theorem.

“I’ve been driving for hours and thinking,” he says. ”What is the source of confidence?” he asks again. Okay, I heard him right the first time. I take a stab at it. “I don’t know – you take something you’re good at and draw strength from it?”

“Two places,” he replies, ignoring my effort. “Options and deeply-held beliefs.” He explains. “It’s easier to take risk when you’ve got a plan B, and the most confident people always act like there’s a plan B. Even if they can’t see it, they believe it’s there or that it will be there if they need it.”

You create options for yourself by building expertise and by being known for as much. Belief, while it can be built over time from a track record of success, starts with self-esteem, created in the elusive soup of genes and early childhood experiences. It is not quickly or easily altered. You start from a position of believing you are “worth it” or not believing, and the foundation of that belief is set years before you ever consider building an expert practice. Propped up by this core belief of self-worth are others. You believe there’s a good fit. You believe you are the right person for the job. You believe things will work out. If you’ve come through childhood with high self-esteem, beliefs come easily and with them the confidence you require to sell your expertise, in the proper manner of the expert.

The lower your self esteem, however, the more options you require to build your confidence. Existing clients, prospects, money in the bank or numerous other forms of fall-back all help to remove gravity and stress from the sale, making it easier to act bravely.

The confidence you derive from your options will also be tied to your capacity. The more employees, office space or other infrastructure you add, the more options you require to keep your confidence up. Before adding capacity ask yourself what this would do to your confidence in the sales cycle.

Control those variables that you can in order to keep your options high and you will create the confidence to do the right thing in the sales cycle and thus demonstrate that you are indeed the expert. Belief will inevitably follow, no matter how badly your parents screwed up.