How to build a second brain for work (without another notes app)

A second brain is a trusted system outside your head for keeping the information you'll need again: decisions, sources, ideas and reference material, organised so you can find and use it when the work calls for it. The term was popularised by Tiago Forte, building on older ideas like David Allen's "get it out of your head". For the short definition, see the second brain glossary entry.

This guide shows how to build a second brain for work that's organised around the work itself, your projects and deliverables, rather than around a growing pile of notes.

Why most second brains die in week 3

Most second brains start with enthusiasm and a new app. Week one is all capture: articles, highlights, meeting notes, screenshots. Week two is all organising: tags, folders, templates. By week three there are hundreds of notes and no clear way back to any of them while doing the actual job. The system becomes one more inbox, and you quietly stop opening it.

The common causes are the same:

• Capturing everything. Volume feels productive but makes retrieval harder.
• Organising by topic. "Marketing" or "Leadership" folders grow forever and never finish.
• No link to deliverables. Notes that never feed a report, a decision or a piece of work have no reason to be opened again.
• No maintenance habit. Without a regular review, the system drifts out of date and you stop trusting it.

The fix is to organise around what you're producing, and to capture less.

Step 1: capture what matters at work

At work, a few kinds of information are worth keeping because they come back again and again:

• Decisions and their reasons. What was decided, by whom, when and why. This is what you'll be asked about in three months. A simple decision log is ideal.
• Sources. The document, page or dataset a claim came from, with a link, so you can check it later.
• Reusable snippets. Paragraphs, email replies, formulas, code and checklists you'll use again.
• Meeting notes with actions. Not the whole conversation, just the decisions, the actions and who owns them.
• Ideas tied to a project. Half-formed thoughts about a deliverable you're actually working on.

And a few aren't worth keeping:

• Articles you might read one day but have no project for.
• Full copies of things that are easy to find again with a search.
• Notes that duplicate a system of record, such as the CRM, the ticketing system or the shared drive.

A useful test before saving anything: "Which project or responsibility will this help, and when?" If you can't answer, let it go.

Step 2: organise with PARA and "one project = one place"

The PARA method, from Tiago Forte, sorts information into four categories by how actionable it is:

The insight that matters most for work is that projects come first. Organise by what you're delivering, and reference material earns its place by serving a project.

Then go one step further: one project = one place. Everything a project needs (the brief, the working document, sources, meeting notes, tasks and decisions) lives together, not scattered across a notes app, a drive, email and chat. When you sit down to work on the project, you open one place and the context is all there. When the project ends, you archive that place in one move. This is the same principle behind organising work by project rather than by app.

Step 3: distil and express

Capture and organisation are only half the system. Forte's CODE framework (Capture, Organise, Distil, Express) puts the emphasis on turning notes into output.

• Distil means reducing a note to what matters. Highlight the key passages, then write a sentence or two in your own words at the top: "What this means for the project."
• Express means using it. The note becomes part of a report, an email, a decision or a presentation. Once a note has fed a deliverable, it has done its job.

Practical habits that help:

• Write a one-line summary at the top of every note you'll reuse.
• Keep a "draft" document in each project and pull distilled notes straight into it.
• Reuse finished work: a good proposal is a template for the next one.
• Keep the source link next to every distilled claim, so you can check it before it goes into something that matters.

Step 4: the weekly review keeps it alive

A second brain only stays trusted if it's maintained. David Allen's weekly review is the habit that does it: a regular session, typically 30–60 minutes, to clear inboxes, update projects and decide what's next.

Weekly review checklist for a work second brain:

1. Empty your capture inbox: file each item into a project, an area or resources, or delete it.
2. Go through each active project. Is the next action clear? Is anything stuck?
3. Add any decisions made this week to the decision log.
4. Archive projects that finished.
5. Check upcoming deadlines for the next two weeks.
6. Look at areas and ask whether anything needs to become a project.
7. Pick the two or three priorities for next week and put them in the calendar.

If the review takes longer than an hour, you're capturing too much.

A worked example: the monthly client report

Here's how the system plays out for an account manager who writes a monthly performance report for a client.

Capture. During the month, three things get saved to the client's project: a note from a call where the client said their priority had shifted from leads to retention, the link to the analytics export, and a decision that paid social would pause for two weeks. Nothing else. The industry newsletter with a vaguely relevant article stays in the inbox and gets deleted at the weekly review.

Organise. All three items live in one place for that client, beside last month's report and the open tasks. There's no separate "analytics" folder or "meeting notes" notebook to check.

Distil. Each item gets a one-line summary on top: "Client now measures success by repeat customers, not new leads." "Paid social paused 4–18 Sept, so expect a dip in that channel." The source link stays attached.

Express. When report day comes, the account manager opens the project and the story is already there: the shifted priority explains why the report now leads with retention, and the decision explains the dip before the client asks. The report takes an hour instead of an afternoon, and nothing in it is a guess.

Review. At the weekly review, the decision goes into the decision log, the call note's action ("send a retention benchmark") becomes a task, and last month's report moves to the archive.

Notice what's missing: no elaborate tagging, no reading list and no knowledge graph. The second brain did one job, which was having the right context ready when the work started. Scale that to every active project and you have a system that pays for itself every week.

Signs your second brain is working

• You can find last month's decision in under a minute.
• You reuse finished work (proposals, reports, checklists) rather than starting from blank pages.
• Starting a work session takes minutes, not a search through four apps.
• The weekly review feels quick, because there's little junk to sort.
• You trust the system enough to stop keeping things "just in case" in your head.

If none of those are true after a month, simplify: fewer captures, fewer categories and one place per project.

Step 5: choose a tool (an honest comparison)

Any of these can work. The best tool is the one that matches how you retrieve information and that you'll actually open every day.

Notion, Obsidian and OneNote are notes-first: you build structure on top of notes. Plexii is work-first: each desk is the place a project lives, and notes are one thing on it. Pick whichever matches the problem you actually have. Local-first software like Obsidian and Plexii keeps your files on your own computer, which matters if your work is sensitive.

Step 6: a free second brain template

You can set this up in any tool. Here's the structure:

Second brain
  Inbox                   (capture anything, empty weekly)
  Projects
    [Project name]
      Brief and goal
      Working draft
      Sources             (link + one-line summary each)
      Meeting notes       (decisions and actions only)
      Decision log
      Tasks
  Areas
    [Responsibility]      (standards, recurring checklists)
  Resources
    [Topic]               (reference you've actually used)
  Archive
  Weekly review checklist

In Plexii, each project in the list becomes a desk with those pieces already on it. Browse the desk templates for ready-made starting points, such as a weekly reset desk for the review. A downloadable version of this template for other tools is coming to this page.

How Plexii relates

Plexii is built on the idea that every task gets its own desk. Instead of a notes app on one side and your files, email and documents on the other, a desk holds the working document, its sources, the tasks and the decisions for one piece of work. That makes it a second brain organised around the work, not around notes, and the weekly review becomes a walk through your desks.

The free tier is free forever for personal use, Pro is US$12 a month or US$120 a year, and teams can try it free for 14 days.

Second brain plus AI: where it helps, and where to be sceptical

AI assistants are good at some second-brain jobs:

• Finding things. Asking "what did we decide about the pricing tiers?" across your notes is faster than searching folders.
• Summarising. Turning long meeting notes or a pile of sources into a first-draft summary.
• Drafting. Pulling distilled notes into a first draft you then edit.

Stay sceptical about three things:

• Sources. AI can state wrong things confidently. Use tools that show where an answer came from, and check the answer before relying on it.
• Consent and privacy. Client documents, personal information and confidential material may not be yours to send to an AI service. Know what leaves your computer and get consent where it's needed.
• Thinking. Research on cognitive offloading shows that people readily hand mental work to external tools, and that their judgement of when to do so isn't always accurate. Let the system remember for you, but still do the deciding yourself.

Common questions

What is a second brain?

A trusted external system for keeping and retrieving the information you need for your work and life, such as notes, sources, decisions and ideas, so your head is free for thinking rather than remembering.

How do I start building a second brain?

Pick one active project, create one place for it, and capture only what that project needs: the brief, sources, decisions and a working draft. Add a weekly review. Expand to other projects once that works.

What is the PARA method?

A way of organising information into Projects, Areas, Resources and Archive, by how actionable it is. It was created by Tiago Forte.

What's the best second brain app?

There isn't one best app. Notion suits teams that build databases, Obsidian suits people who want local Markdown files, OneNote suits Microsoft workplaces, and Plexii suits people who want each project's files and notes in one desk. Choose by how you retrieve information.

Is a second brain worth it for work?

It is if it saves you from redoing work. Finding last quarter's decision in seconds, or reusing a proven proposal, pays back the time. A system you have to feed but never use isn't worth keeping.

Sources

• Tiago Forte, Building a Second Brain (opens in a new tab) (2022).
• Tiago Forte, The PARA Method (opens in a new tab), Forte Labs.
• David Allen, Getting Things Done (opens in a new tab) (2001, revised 2015).
• Evan F. Risko and Sam J. Gilbert, Cognitive Offloading (opens in a new tab), Trends in Cognitive Sciences 20(9), 676–688 (2016).