The Two Minds Running Your Life

Originally shared in Tuesday Notes on April 21, 2026.

Quick question before we start.

How many decisions do you think you make in a day?

The research estimates it somewhere around 35,000. This sounds impossible, until you realise most of them aren't really "decisions." They're mostly your brain on autopilot. Which shoe to tie first. Whether to trust the stranger's face. When to reach for your phone.

Most of our lives happen on autopilot. And most of us never notice.

That's where this new series starts.

For the next six weeks, I want to talk about the quiet ways our brains run the show without asking us. Biases, shortcuts, little patterns that shape how we love, how we spend, how we see ourselves. Most of us live our whole lives inside them without ever noticing.

And to understand any of them, we have to start with the work of one man: Daniel Kahneman.

Kahneman was a psychologist who won the Nobel Prize in Economics (yep, economics, as a psychologist, which tells you everything) for showing that humans are not the rational decision-makers we like to think we are. In his book "Thinking, Fast and Slow" (which I can absolutely recommend), he laid out a simple idea that changed how we understand the mind.

You basically have two systems running your brain.

System 1 is fast, automatic, emotional. It's the one that caught the ball before your brain knew it was thrown. It's how you drive home without thinking. It's also the one that decides, in 0.1 seconds, whether you trust someone's face.

System 2 is slow, deliberate, effortful. It's the one doing your taxes, writing the careful email, holding back from saying the thing at dinner out loud.

Here's the part that really surprised me when I first read it: we use System 1 for roughly 95% of our decisions.

95% percent of your life is your fast brain on autopilot.

Which sounds alarming, until you realise it actually has to be that way. If you had to consciously think through every choice, you'd pass out from exhaustion by 10.00 am. System 1 is a gift. It's how your brain saves its battery for what actually matters.

However, there is a cost.

System 1 is fast because it takes shortcuts. And those shortcuts, the ones that help you avoid a car or read a room, are the same shortcuts that become cognitive biases. The same autopilot that keeps you alive is the one that keeps you dating the wrong type of person, staying in the job too long or believing a story about yourself that stopped being true years ago.

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Tuesday Brain Snack

Your brain uses about 20% of your daily energy, despite being only 2% of your body weight. That's why System 2 (the careful, deliberate thinker) is so metabolically draining, and why your brain will do almost anything to avoid using it. It's not because you're lazy. Your biology is literally designed to preserve and save on effort. Which is why knowing about a bias isn't enough to stop it. Your fast brain will always get there first.

So What Do We Do With This?

The goal of this series is not to shame System 1. You need it. I need it. It's the reason we can function.

The goal is to notice. To catch the autopilot in the act. To build a small gap between the shortcut and the choice, just big enough to ask: is this actually me or is this my brain being efficient?

Because once you see it, you can't unsee it. And once you can't unsee it, you get to decide.

Next week we start with the bias that runs almost every relationship, argument, and self-image you have: confirmation bias. The reason you keep finding evidence for what you already believe, and the reason changing your mind feels like losing.

Bring your coffee. Or your taco. Either works.

One Question to Sit With This Week

What's one thing you do every day on autopilot that you've never actually chosen?