I'm putting these in multiple posts so it isn't overwhelming.
So, now how the parts work together. This is important because it shows why thinking positive works. It isn't just something your therapist wants you to do to feel good. It has a function.
As does medication which will be separate.
Every thought that makes it to the brain goes through Hippocampus for direction on it's way to Hypothalamus. Hypothalamus decides how you should think toward this thought or your body react if that is needed. It has a big job and is a big part of your brain. Positive thoughts go direct to Hypothalamus because Amygdala doesn't need to look at them other than to say, not my concern.
Negative thoughts go directly to Amygdala for contemplation and it's reaction comes from it's memory. It's memory is separate from other memory yet is controlled by feed back from hypothalamus. It can change. Most negative thought only calls for normal anxiety. Core beliefs can exaggerate this reaction. If Amygdala's memory says to panic you will and very fast too. Once set in place Amygdala makes the long arduous trip through contemplation deciding if panic is really necessary. In the mean time it has also sent a signal to Hypothalamus to react. This is where your symptoms come from. They now stay up till Amygdala says to stop. Hypothalamus is a slave to memory. It does nothing on it's own. It does what past memory says to do. Negative and Positive are it's masters.
To recap, positive thought gets a positive reaction, negative gets a negative one (fear)
None of this happens on it's own. It takes direction from you.
Controlling factors are mood and core beliefs.