Not advice-column wisdom. It interviews your actual life for the material — the mistake that taught you, the person you almost were — and builds a letter only you could have written.
Help me write a letter my grandchild opens on their 25th birthday. I might not be there. Make it worthy of that.
What I'll give you: their name and age now, and answers to whatever you need — but you only get to ask me for FIVE inputs, so choose them like a biographer, not a gre