A majority of the people never heal, because they fail to come out of their heads, because they stay there replaying corrupted scenarios. Whatever you may feel and experience, it is all a result of your internal representations of those things. Many people are haunted by dark memories of their past. The flashes and images of those traumatic times give them nightmares, generally leaving them helpless and paralysed.
Many a times your brain runs the same image from your past over and over again. It shows you all the things you no longer want to see. If same is the case with you, all you need to do is simply turn down the lights in your head. Make this image smaller, move it farther away, dim the light, blur the image out all the way. Continue doing this again and again, each and every time.
Remember, you need to boost up the sound and light of all the positive messages in your brain and dim the flashes and voices of all the negative ones. Do this each time, until you change the movie that is automatically being played in your head. Give it a shot and feel the difference.