To continue with simple, yet great parables and metaphors, after the apple, here is a sweet one specifically referring to sales, but also largely applicable to any situation where one has to exert influence.
A young Salesperson was disappointed at the end of a meeting. that did not go the way he hoped. Fact was, he had lost an important sale, and he could not get himself to get over it. Yet, he did not seem to clearly understand why he had lost the sale. In discussing the matter with his Sales Manager, the young man shrugged.
“I guess,” he said “it just proves you can lead a horse to water, but you can not make him drink.”
“Son,” the Sales Manager said, “let me give you a piece of advice: your job is not to make them drink. It’s to make them thirsty.”