One of the helpful techniques I've learned with Paul Hughes' 4R mental training course (interview here) is the defusion technique from ACT (acceptance and commitment therapy). When we are shooting (and in many other areas of life) we are going to have thoughts and emotions we cannot control, they just pop up and start playing with our minds. What we can do (this is the core of ACT defusion) is change how we relate to them, so that we can reduce their impact. This has been a life saver.