I am not an expert in Neuro-Linguistic Programming (NLP) but I have used a few of these techniques to trick my brain from thinking badly about a negative event thus reducing the emotional reaction each time thoughts of the negative event arrive in my head.
NLP provides an understanding of the mental and cognitive processes behind our behaviour to certain situations. We can actually reprogram our brain using these techniques. By changing the way we think about a situation we can change our emotional reaction and our perception as a result. So how does that work?
Inside our brain is the amygdala which is responsible for our emotions. When someone attacks us for example, the amygdala sends a signal to alert our emergency response mechanisms so that we can fight or flee. The amygdala is attached to our hippocampus, this part of our brain stores our long-term memory. So, when we have a bad event the amygdala alerts our response functions and the bad memory is stored for future reference.
This is the brain's way of protecting us so that if a similar event happens in the future we are ready for it. The hippocampus and amygdala have worked in tandem to burn or 'brand' that bad memory into our brain.
Taking the example of someone attacking us, every time you have some kind of a reminder or connection to that attack you also have an emotional reaction. The connection to the attack could be a smell, a sound, a sight, or just a random thought of the attack. When you are reminded of the attack, the hippocampus alerts the amygdala and you have the same emotional reaction as you had when the attack first occurred.
While you can never completely remove this bad memory, you can lessen the subsequent emotional reaction each time the thought of the attack comes into your head. In your mind, take an image of that negative event then put a picture frame around it. Once you have the image inside the frame you then hang the framed image on a wall. Now stand back and look at the picture again. It is just a harmless picture. Our brain has been tricked into thinking the event never actually occurred. You may have to do this several times to embed the effect.
There are many other techniques, Dr Google can show you these. I found this one very good, along with flicking an elastic band around my wrist each time I had a negative thought. The pain from snapping band distracted my brain.