Old letters are full of grocery prices and weather reports. The ordinary stuff is what people end up treasuring.

People writing letters put in the small facts because there was nothing else to say, and the small facts turned out to be the part worth having a century later. What bread cost, how cold it was, who came by on Sunday. Ordinary detail survives better than announcements, because it shows what living there was actually like.

Put something unremarkable into your next message to somebody far away: what you ate, what the weather did, what the street looks like now. It reads as filler and it is the part they keep.