You need something to write in and two minutes. That's it.
The minimum viable first entry
Open a notebook, a notes app, or a voice recorder. Write, or say, what happened today, in one to three sentences. That's a complete entry. Richard Burton's 44-year diary has entries that short throughout it: length was never the requirement, continuing was.
You need
- A notebook, a notes app, or a voice recorder: any one of them
- Two minutes at roughly the same point in your day
- Nothing else. No prompts, no template, no minimum word count.
Day 1
Write down one thing that happened and, if you want, one line about what it meant. Don't reread it. Close the notebook or the app.
Week 1
Keep it at the same rough time each day: after breakfast, like Rahul Dravid, or before bed. If a day gets missed, don't go back and fill it in. Write today's entry normally the next time you sit down.
When you miss a day
Nothing to fix, and no streak to protect. Eugène Delacroix's diary has a two-year gap in his twenties before the 16-year daily run that made it famous. Amitabh Bachchan is the exception, not the rule: he hasn't missed a day since 2008, but every other long-running diary on record has gaps. Pick back up wherever you are.
Making it stick
The diaries that lasted decades weren't written under pressure to be interesting. Rahul Dravid describes his own entries as "as boring or as dumb as you can say." A boring entry that gets written beats an interesting one that doesn't.
Try it by voice: Brain Dump: say what happened in a sentence or two on the days a notebook would have gone untouched.
For the full history and what the research on diary-keeping actually shows, see the daily diary method page.