Take a look at yourself from the past. 10 years ago, 15 years ago, 5 years ago. Just pick some random time. Do you think you've learned anything? Is there anything you would tell yourself from that time, if you had a chance?
I'm choosing myself 11 years ago. I would have been 16 years old. The height of my rebellious streak. I had green hair, and always thought I was completely fine being an ass as long as I had my two or three friends. I wasn't too bad. I never vandalized anything, talked back to adults too much or caused fights, but still did a lot of things I regret. I smarted off to people a lot, and did a lot of things to stand out.
I'd like to think I've become at least a little bit wiser, but I don't really know. I still make a lot of the same mistakes. I would tell myself not to try so hard to stick out so much. I look back and cringe at dumb things I did.