The order matters because each step narrows the frame: the date fixes the moment, the description of today supplies the raw material, and only then do the questions have something to lean on. Hiding comes last so the letter is finished and unedited before it gets a home. Follow the sequence and you end up with a record rather than a wish list.
Step 1: Pin the moment before any prose
Everything else on this page is written for a reader whose sense of now will not match yours, so the first job is to pin the moment down. Put the full date with the month spelled out — '14 March 2026, age 34' — not a bare year, and never a numeric date like 03/04 that future-you has to decode. Age is the load-bearing part: it converts the calendar into a comparison that hits differently. Someone who writes 'age 29' and opens it at 34 confronts the gap between how old 29 felt and how old 34 looks. People skip the age because it feels redundant next to the year, but a year is a fact and an age is a mirror. Write it in ink at the very top, before any prose, so the letter can never be mistaken for an undated draft.
Step 2: Evidence beats a highlight reel
Here is what most letters omit: evidence. With the date and age already fixed, the page needs specifics that a summary would erase, so describe an ordinary weekday rather than a highlight reel. Name the actual worry — 'the contract renews in June and I still don't know if I want it to' — and the actual joy, which is usually smaller than people expect: Thursday walks with Priya, the good bakery two streets over. Then three mundane facts: what lunch costs, what you're reading, how much rent went up. The non-obvious part is which of these ages well. Big anxieties read as weather that has long since passed, while prices and routines read as archaeology. A line like 'a coffee is 3.80' will tell future-you more about this year than any paragraph about your five-year plan. Skip the summary and the letter becomes a mood with no floor.
Step 3: Three questions that can be answered
A question written cold tends to be vague, but now that the letter contains a date and a snapshot of an ordinary week, the questions can be specific enough to answer. 'Are you happy?' fails — it is unanswerable in a margin and future-you will skip it. 'Did you finish the Portuguese course?' works, because a yes or no opens onto something the reader can then explain. Aim for three that pull in different directions: one about work, one about a person, one about a habit you keep failing to start. Leave a blank line under each so answers have somewhere to go, and tuck a pen in with the letter if the hiding place allows it. If a question already contains your preferred answer, it is not a question and future-you will read it as an instruction.
Step 4: One hope, one warning, both specific
Two lines carry more weight than the rest of the page combined, and they belong after the questions rather than before, because three concrete questions have already forced you to think about what you actually want answered. The hope should be small and checkable: not 'be happy' but 'I hope you have stopped saying yes to Sunday meetings.' The warning is the harder half and the more useful one. Write it about your own pattern, not about other people: 'You get restless in the second year of anything — you did it with the band, the flat, the gym. Wait four months before you decide.' Naming the tell is what makes a warning land, because future-you will recognise the feeling long before the argument. A warning that is really a complaint about someone else reads as a grudge, and a hope vague enough to fit anyone is a fortune cookie.
Step 5: Hide it where you'll forage later
Only now, with the ink dry, should the letter get a home — picking the hiding place first tends to shape what you're willing to write. Choose somewhere you'll still be in five years or will definitely empty by hand: inside a specific book you own and won't lend, taped behind a framed photo, in a labelled box with your tax files. Three rules. Not somewhere damp. Not somewhere a house move will make a stranger the first reader. And not somewhere you see daily, because the letter becomes wallpaper and you'll peek in month three. Then set one calendar event for the month and year, titled 'open the letter', with the hiding place written in the notes. If the letter travels with you to a new address, that event is the only thread back to it.
A phone reminder vanishes the moment you dismiss it, leaving no trace that it ever counted for anything. A paper strip taped somewhere you'll actually see it gets visibly shorter as you work and stays put until the last line is cut away. Print this one, write the date on it, and keep it beside the letter until it's done.