If life and sales could be wrapped up in one word, that word would be Persistence.
Persistence is the key to focusing on product knowledge until "revelation" comes. It will help you to endure the arduous tasks of prospecting and business development until success comes. When the tank of enthusiasm is empty, persistence is that reserve tank that can get you the next 5 miles until you reach the next filling station. Persistence is the ultimate fail safe against failure. Persistence says "It is not over until I win" - Les Brown.
Persistence can't be overdone.
You can't make too many sales calls, you can't become too much of an expert in your product, etc. In the "artful" side of a sales interaction, there is a difference between persistence and being a nuisance - you inherently know the difference. Time and experience will help you differentiate, but the old rule "when it doubt, go for it" applies. Some sales people use not wanting to be a pest as an excuse for their approach avoidance. Persistence obliterates procrastination and demands immediate, direct action. It leverages the "necessity is the mother of invention" power of innovation and imagination. Even if you don't know what to do next, if you persist you will find a way. A way must reveal itself!
Persistence is an outward show of faith.
It is action oriented and not just idle talk. In the Bible, James Chapter 2 says (paraphrased) "One man says he has faith...one man does faith filled action". It concludes - the man with "real faith" is the one who is doing! Start doing the right things and keep doing them until you win!
Persistence is Insistence.
It becomes a demonstration of conviction. You may be turned away but you are still committed to find a way! As LeRoy told Matt, "Once a man is convicted and acts on that conviction, he will be successful in whatever he puts his hands to do."