I had a substitute high school teacher one day who made us all write letters to ourselves, then sent them to us like 20 years later long after we'd forgotten about it. It was amazing!

Did you achieve all of what you hoped you'd do?

I think it would be a great self-introspection exercise to “respond” to this letter. You don’t even need a letter- just write to your past self and tell him/her what you’ve achieved, what you’re proud of, what you wish you’d done differently, what you’re unsure about for the future.

futureme.org. I remember writing some about 10 years ago.