Savour it and now think about how you achieve it. Did you even once thought about your past? If you didn't, that answer probably isn't yours and someone is running your life.
This question is a common question and is asked by people who are scared to face their own past. Don't get stuck, remember what you did wrong no matter how stupid it is and answer it in the future correctly
99 percent of everything we see, do, and make is based from the past. We would literally have to start from scratch if we did not know about the past. For example we would not have technology, modern appliaces if we did not have past. This is a stupid question
For me the most obvious reason for not forgetting the past is because the past improves our lives in the present and future. The past provides us with experience which gives us information that usually helps us guide our decision based on what the outcome we are trying to achieve is. If in the past I get a dog and it dies because I didn't give it adequate care, then now I know to learn more information regarding dogs in order to take better care for it.
Forgetting our past is the worst way to live - sure, we may have a bad history or memory, but we would live everyday constantly starting from point zero and trying to make our way to 100. What makes this life so special is being able to learn from our past and having the ability to build a better tomorrow from our yesterday.