Have you ever looked into a body of water and looked at a reflection of yourself? What made us who we are is something that is hard to explain. No, we weren't just made up of good experiences, some experiences were bad, but they also helped make us who we are today.
If we cannot forget the bad experiences, they are going to impact us for the rest of our lives. What people need to do is realize that a bad experience happened and let it go. No, it may not be totally forgotten, but at least saying it happened, and I am not going to let it impact the rest of my life is important. Being able to accept it happened but not dwell on it will make you a better person. You may have to talk through the experience with someone or write it down before you can put it in the back of your mind.
Looking into who you are is something we all do from time to time, and it's important to look at the good experiences and be happy with them. The experiences that weren't, so good are lessons that we learned and things that cannot be changed from in the past, but experiences that we don't want to repeat. We need to remember the good experiences and enjoy those feelings, as those are the experiences that have made you who you are and why you smile and feel good about yourself.
Knowing how to accept that a bad experience happened and letting it go will help make that reflection of yourself even better. You will know that you are a stronger person for letting it go.