Not sure you should ever forget life experiences i believe there is a difference of being proud of what you did and knowing what God turn you away from. a testimony is a look at what a God did for me. This is a way to allow Gods glory to shine through you, a way to reach the world through experiences. People struggle and they need some one to help them through that actually been through what they are experiencing, I've never been an acholoic or done drugs, I cant personally help, more times then not if I did try it would seem more like picking, judging and preaching and that does more harm then good. Can't bring people down further than what they are, not what God attended. But I have a brother in law that was into drugs bad. But God took over his life, and now he had a reach out program for addiction that he preaches and runs. He talks they listen because he has been through it they know he has struggled, and now they see where he is in life, and why and who changed it.
When you take in Gods spirit and get saved you become a minister of God, testimonies are just one way to minister his word through experiences you had, not meant to be forgotten, but also not meant to be idolized, only meant as a reminder to you and everyone else that you are born again, new man that never wants to go back that path because God himself helped me and chose me to get way from the wickedness that would do nothing but caused me death.