Some interactions with customers almost seem to be divinely inspired, while others feel like you’re trudging though mud and muck, getting nowhere fast. What’s the cause of these very different scenarios?

The Inspired Sale, one in which the buyer feels a compelling need to buy and buy from you, always has two components: trust and compulsion. Without both of these, selling becomes a difficult, if not impossible task.

Without trust and compulsion, you experience Shields Up, the sales equivalent of the shields in spaceships in science fiction. Buyers deploy ten different shields to protect themselves from a sales pitch, especially when they don’t trust you nor feel a compelling need to buy from you, even when they have a need you can fulfill. Trust must be built first before compulsion can move the conversation towards a mutually beneficial relationship where the needs of all parties are met.

PREMIUM CONTENT: The fastest-growing U.S. job markets

If a buyer can benefit from what you do and trusts you, yet, doesn’t feel an irresistible urge to buy, you have someone who is just going through the motions. He feels good, you feel good, yet these good feelings are doing nothing to benefit either of you long term. In order for a trusting buyer to gain the compulsion to buy, the salesperson must engage a collaborative dialogue where the buyer sells himself on buying and buying now.

You get a resistant buyer when she has a need to buy but doesn’t trust you enough to buy from you and your company. Time, energy and effort to build trust are the next course of action.

Trust and healthy compulsions to buy are each, in and of themselves, valuable commodities. In combination, they create an alchemy that produces golden results for everyone. The task of every salesperson who wants to sell more is to ensure that both elements are part of every relationship.

MORE: Creativity in sales: Common myths