Chances are that right now, you are at the wisest you have ever been.
Whatever beliefs you might have had when you were younger, you’ve had time to reflect on them and change them to beliefs that are better.
You’ve had experiences your younger self didn’t expect, and you’ve hopefully learned from those experiences.
You’ve read books your younger self wouldn’t have enjoyed, agreed with, or known about.
You’ve gone through education, both formal and informal, and that has changed you.
All of these things have (hopefully) left you wiser than your younger self. The question is: what do you do with this wisdom?
Write it down. Write down the lessons you’ve learned that you wish you could give to your younger self. Figure out what lessons would have given your younger self an edge, or allowed them to avoid critical mistakes. Turns these lessons into concrete principles that you could teach your younger self.
Obviously you can’t actually go back in time and give these lessons to a previous version of you – but you can teach them to others. Whether it’s “students” learning something you have experience with, friends and family about to make a mistake similar to ones you’ve made, your children, or simply random readers of your blog, figure out the lessons you’ve learned and teach them to others. Get feedback. Make your ideas better. Reflect on your principles. Make them even better. And even if no one listens to you, you can at least try to make yourself a little wiser by having concrete lessons and principles to look at – and improve as time goes on.
You can’t change the past, or give the lessons you’ve learned to your previous self. But you can reflect on what you’ve learned, and make the world a tiny bit wiser.