I want to tell you that in my spiritual path the first book that came to my hands is called "The Secret" by Rhonda Byrne. This self-help and motivational book opened my eyes and helped me understand many things.
The law of attraction says that everything you think becomes reality. In other words you attract what you think. This simply means that if you think positive, you attract positive; and if you think negative you attract negative.
It really is a concept that sounds easy but many people still ignore this simple law.
This law applies to various aspects of your life such as health, money, love, happiness, relationships, etc.
If you apply it, you will achieve happiness in all areas of your life.