In your next interaction with a customer, try this: Be irreplaceable.
If you wait tables, make sure that the customer's experience depends on you, and who you are, and would have been different with another server who served the same meals.
If you are a technology consultant, make sure that your client's experience would be totally different if another consultant were delivering the same advice.
If you are a doctor, make sure that your patient's experience is made special by who you are, and would be different if another doctor delivered the same diagnosis.
Relationship-building encounters don't happen between "waiter and customer," "consultant and client," or "doctor and patient." They happen between human beings. It is, of course, critically important to treat your customer like a full person, and honor what makes her unique. But that is only half the equation. Make sure that you represent yourself in the encounter, not as a representative of your job role, but as you. Interact with your customer in a way that could only be done by you, a way in which another person could not substitute for you without making the experience different.
Early in my days as a consultant I had a breakthrough moment. I realized that I didn't want my clients to think of me as "our marketing consultant, Steve," but as "Steve, our marketing consultant." This is not a subtle distinction. It's the difference between being replaceable, and irreplaceable.
In one sense, being irreplaceable isn't easy. But in another sense it is, because there's no one else on earth like you. Be you. Be irreplaceable.
[See more by Cool Friend Steve Yastrow at www.yastrow.com.]