See and stay with the contradiction. The more we don't want any past painful experience, the more we experience it. To demonstrate this principle in the physical, when we put the palms of our hands together and use the right hand to try to push the left hand away, we find it can't be done because the left hand pushes back with an equal amount of force. Similarly, whatever it is that is suffering can't push away its pain. In those unwanted moments, where suddenly a thought about the past comes along to entice you into it, telling you how to be or what to do, inwardly become aware of that same pressure of resistance. Try to catch even a glimpse of the fact that, in that moment, what you're resisting and suffering over isn't the moment itself; notice that your mind can't stop looking at and reliving the painful event that it says it doesn't want. All you need to see is that contradiction in that consciousness. Don't answer or talk to yourself about what you see, simply stay with awareness of the contradiction. When you clearly see the contradiction, then you will understand who you are not, and you'll also know what not to give your life to.