I once was a sales associate for Eddie Bauer. Each of the associates, like most sales-oriented positions, had manager-set goals. I would constantly sell 200-300% of my goal. The general manager asked me one day, "How do you do it? How do you sell that much in revenue?" I replied, "It's simple. I'm not here to sell clothes."
"What?" the manager ask. I continued, "Yep. This is, after all, a clothing store so I figure they're coming in here to look at clothes. My job is to just make sure they enjoy their stay."
I was the only sales associate who would spend time playing with children while the mother shopped for clothing. While I'm ringing up $300-$400 at a time, the moms would tell me that this was the first chance they've had to shop all day. I would also help the little old ladies wrap their Christmas gifts.
Each of the shoppers had two things: 1) a need; and, 2) a want. They couldn't satisfy their want until someone/something met their need.
The shoppers wanted to buy clothes, but needed someone to entertain their child(ren). Or, they wanted to buy a gift, but needed help wrapping the present.
This is often the case in any situation - the need gets in the way of the want. Think about it in an everyday, general sense. "I'd love to buy [insert your desire here], but I need to put my children through college." Or, even more basic, "I'd love to get a [your desire], but I need to make sure I can put food on the table first."
Often times, the difference between the sale of the want, is the need.
First, give someone what they need; then, they'll buy what they want.