The Law of Attraction basically says, "Like attracts Like." Therefore, whether you think about Good Things,... or not so Good Things, you WILL draw that to you based on the vibration of energy you are emitting and your attention to it.
For example: have you ever noticed that when you start off "having a bad day", more negative things tend to keep happening...? Usually, it's because you have continued to focus on the negative, and thus keep that energy flowing in that same direction. But...if you are able to "brush off" the moment and continue on with your day, you will likely have a much more pleasant outcome!
My personal experience with the Law of Attraction was initially introduced through the book The Secret- By Rhonda Byrne [also available in Movie and audio format]. This is still a primary reference for me, but even more than the original, I connected very strongly with the sequel book The Power- By Rhonda Byrne. Both are great self-help tools!
Lastly, the teachings of Abraham Hicks, Wayne Dyer, Louise Hay, and MANY MORE, are basically "household names" for me in my personal inspiration and mission.
All of these great resources are available for access and more information through HayHouse publications. Click the image to go to their website!
...If you are spiritual, enjoy New Age tools, or just can't get enough of the self-help wisdom in the world... this IS the go-to resource out there!