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

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.