Building Your Second Brain

Read time: 2.5 minutes

I used to have brilliant ideas in the shower, on a flight, mid-conversation. By the time I opened my laptop, they were gone. I had been running an eight-figure business off scattered voice notes, a Notion to do list, and whatever I could still remember at 11pm. The irony was not lost on me: I had built meticulous systems for every function of my business. I had no system for my own thinking.

TODAY AT A GLANCE

Your brain is not a storage device. It is a processing device. Stop asking it to do both.
A second brain built in Obsidian and Claude takes under an hour to set up and changes how you think permanently.
The save-for-later habit is a trap. The only content worth saving is content you immediately process.

[the thought]

The Save-For-Later Paradox

Every founder I know has a version of the same problem. A Substack article bookmarked on Thursday. An Instagram reel saved on Saturday. A podcast episode flagged with the intention of coming back to it. By Monday, the queue has grown by twelve more items. None of them ever get touched.

The save-for-later habit is built on a fiction — that there is a later. There is not. There is only now. If the idea does not get captured and processed now, it is functionally lost even if the link still exists in your bookmarks.

I have deleted entire bookmark folders containing 400 links. I had never processed a single one.

[the tool]

What A Second Brain Actually Is:

Tiago Forte's framework in Building a Second Brain is simple: take knowledge out of your head and into a trusted external system. The point is not organisation for its own sake. The point is that your brain is freed from the work of holding information and can focus entirely on connecting and generating it.

The system I landed on is Obsidian, a (free) local-first tool where every note is a plain markdown file that lives on your computer and belongs entirely to you. No subscriptions. No proprietary formats. No lock-in.

My vault is structured around what I actually do and think about:

00 Inbox: fast capture. Ideas, links, half-thoughts. Nothing gets processed here; it just lands.

01 Areas: the ongoing domains of my life and work. Each with its own index. My health and fitness goals, philosophy, curiosities, business thinking.

02 Projects: each active project has its own folder. Meeting notes, decisions, open questions, references.

03 Resources: organised reference material. AI and tools, business strategy, core themes, YouTube notes, people and relationships.

04 Archive: anything no longer active but worth keeping.

The steepest learning curve is simply getting used to Obsidian if you have not used it before. The setup itself takes less than an hour and I've linked the exact YouTube links I used to get going below. It will look something like this example as you continue to build it out:

Where Claude Comes In:

Once your notes are inside a vault, you can connect Claude to them. This is where it gets genuinely interesting.

I can ask: what did I write about this acquisition six months ago? What are my open questions on this topic? What patterns appear across everything I have captured this year? And I get synthesis from my own thinking. The more you input, the smarter your second brain becomes.

The workflow:

Download Obsidian (free). Create a vault — a folder on your computer where every note is a markdown file you actually own.
Start capturing. Meeting notes, book highlights, random ideas, half-formed thoughts. Do not organise yet. Just capture.
Open Claude. Upload your notes or connect your vault. Now ask it questions about what you have been thinking.
Build the habit: capture in Obsidian, think with Claude.

The vault is entirely personal. Mine is business and thinking heavy. Someone else's might be deeply personal, creative, or both. The system is whatever you need it to be.

[the action]