The Universe, God, Source, the All... However you want to label it, just know that it loves to play with us all.
I have many ways of interpreting this theory based upon my own experiences with it but for this story i will focus only on the one which may be a little less personal but will allow you to have an example that you may have observed in your own life.
I have, this year been in charge of four cars, each car varying in rarity. When i am in each car, the universe shows me more drivers on the road driving the same said car. When i move myself into a different car the universe shows me less of the previous car and more of the newer car.
What is this? Coincidence? To the magician there is no such thing as coincidence, just cause yet unknown...
To me, this is the classic example of the law of attraction at its finest. For the law of attraction to work, you have to embody the energy; you have to hold the energy for that energy to manifest in your life.
This example is with cars but the same applies for riches and love... You have to hold these in your heart to be able to manifest them... The universe loves to give you what you are, if you hold it in your heart it will do what it can to give you more of it.
Happy Motoring! Happy Attracting!