Results are Likable
It's been said that people work with people they like. Why is that? Is it because likable people are more palatable? The truth is that that people like working with people who deliver results. People hire people they trust. Trust is a key factor in any sales transaction which translates into trust for product quality, brand promise, guarantees, etc.
When we sell, we are transacting trust and confidence that our product/service will "deliver the goods" (otherwise why would we sell it?). The best in the business are generally the biggest advocates for their product/service (i.e. Jeff Bezos of Amazon). They are confident that their solution(s) work and they strive to make improvements daily.
Are you overwhelmingly confident in your product/service? Do you know for a fact that you can deliver results? Are you clear on what those results are? Are you working day and night to ensure your product/service is the best in market? If you second guess the answer to any of these, your client/customer will equally second guess.
Our job is to ensure that our promise delivers results. Nothing else matters.