Perhaps the easiest way to understand this would be to be stop using the words "positive" and "negative". Then we can describe the process like this:
1. Your thoughts create your reality.
2. The sum total of your reality reflects the sum total of your thoughts.
3. Thoughts affect each other. For example, depending on the nature and substance of a thought, it may strengthen or weaken the effect of another thought on reality.
4. Thoughts also work in combinations. They do not necessarily strengthen or weaken each other, but combine to produce circumstances that reflect the features of each thought.
And that is all to say about it really.
The labels "positive" and "negative" can be misleading because there can be a strong subjective element in deciding whether an event is "positive" or "negative".
For example, we may think of being "poor" as a negative event, but then studies on happiness consistently show that the average person in poverty-&-disaster stricken Bangladesh are happier than the average American.
Not all thoughts have equal effect on reality. I believe for example that thoughts accompanied by strong emotion have extra effect on reality. It could be intense fear, or it could be intense joy, or it could be intense anger, or it could be very deep calm.
Deeply-ingrained beliefs also have extra effect on reality, because they are working in the background all the time.
Steve Irwin
believed that he would die young, and suddenly. And so he did. It was not a belief that was accompanied with fear. It was just a deeply ingrained belief, that is all.
In December, my daughter landed up in hospital. It was an extremely stressful time for my family. I later analysed how I manifested it. In retrospect I saw that ALL of us had manifested it - me, my wife, my son, my parents and my daughter herself.
We were co-creators in this experience, which occurred in each of our lives, because we had individually attracted it, even though none of us were thinking the same kind of thoughts (and certainly none of us wre expecting my daughter to fall ill like that, or thinking such thoughts). Analysis here:
Creation & Other Adventures: Cause & Effect
This is the remarkable interplay of the universe. Just as the victim and the robber attract each other, so in any situation involving many human beings acting in different capacities and doing different things, EVERY person attracts exactly what he thinks about, out of the situation.
The idea has been described in different terms, in different philosophies where you'll never hear the phrase "Law of Attraction". For example, the Zen saying that:
"When the student is ready, the teacher will appear"
illustrates the same idea as Abraham Hicks illustration of the robber and victim attracting each other. The student and the teacher attract each other into their respective realities, just as the robber and victim do.