It sounds like your question is, how to stay clear headed?  If so, just know that you have a plan and you are working that plan.  No is inevitable, however how I trained my sales professionals was that customers do have a "will invest line".  When you have met their criteria, they will invest.  You just need to know what their criteria is such as, fixing a problem, lower than previous quotes, better personality, etc.  

​I ​strongly suggest that you take the word "sales" out of your equation.  You are building a relationship so you must LEARN.  Learn their business, learn the buyer, and by all means learn to demystify your product so they understand how you can make their life better.  Hopefully, your business is not a buy once and done.  If so, there are ways to overcome that with effective follow up.  

​Customers don't care how much you know, they want to know how much you care about THEM!