The less you try, the more you get.

There is a concept in pick-up coined as the Cat's Theory - Dangle a ball of strings in front of a cat just out of its reach and that little pussy will play around in trying to touch the ball of strings constantly. This interaction between the ball of strings and the cat could go on for a long time but once you drop that ball of strings, the little pussy messes around it for just awhile and leaves it right away, showing disinterest.

This phenomenon parallels the interaction between a guy(the ball of strings) and a girl(the pussy - pun intended) in life as well. A girl will often and eventually take a guy for granted and grow bored of him if he throws himself on her, appears needy and succumbs to every wish and desire of the girl - pays for drinks, offer to send her to places, sweet talk etc. On the other hand, if a guy shows his interest towards a girl but appears almost out of reach all the time, he is playing his cards right. The less you try, the more you get. If you make your availability scarce but carries your frame well whenever you interact with a woman, she will grow to appreciate your presence more each time you guys rarely meet.

The social dynamics involved here is that people will often perceive what is scarce and rare to be of high value or highly exclusive. A Lamborghini Reventon costs a fuckload amount of money (1 million euros) not only because of its craftsmanship and engineering,but also its value is defined by its scarcity and people's perception on how exclusive it is - only 20 are made and released in the public. Another factor that propels a girl to chase after what is seemingly out of reach is their need to be validated.

Validation? Trust me, as much as girls pretend that they dont like the attention from guys, they fucking do. Most pretty girls are attention black-holes - all they do is soak up the male attention in the solar system of comfort they live in. Therefore, if you carry yourself as that kinda guy who doesnt quite give a fuck (show lack of interest) towards how pretty/hot the girl is, you demonstrate value and pique her interest as she will be left hanging and wondering why this guy isn't attracted to her beauty just like the other guys. Subsequently, she will be inclined to give you response and also gather your response/attention to validate her own qualities.