How To Stop Overthinking Things You Can’t Control

A Cambridge neuroscientist explains what uncertainty is actually doing to your brain and how to work with it

Before I kick off today’s episode, I have to share something with you first because I literally just got off the phone with my publisher.

Healthy Shouldn’t Be This Hard is a Sunday Times Bestseller!

I don’t even know how to write that sentence. It feels completely surreal. The last couple of weeks have been one of the most extraordinary of my life, meeting so many of you in person, hearing your stories, seeing the book in your hands. I wanted to say a personal thank you to everyone who pre-ordered, because that is what made this happen. You did that.

Bloody nuts doesn’t even cover it.

I have so much admiration for anyone who writes a book. Anyone who pours their soul into something and then has to let it go out into the world and hope it lands. It has been one of the most emotionally draining and soul-filling things I have ever done, often in the same afternoon, and your support has meant everything.

It actually links beautifully to today’s episode, because while I was waiting to hear whether we’d made the Sunday Times list, my brain was doing exactly what Hannah Critchlow is about to describe. Sitting in a wave of uncertainty, not knowing.

Turns out there’s a lot of neuroscience behind that feeling.

Hannah Critchlow is a neuroscientist at Cambridge University and author of 21st Century Brain. And what she brings to this conversation is something I didn't expect, not just the science of why uncertainty feels so physically unbearable, but why your brain was actually built for it, and what happens when we stop running from it and start working with it instead.

If I had to distil the whole conversation into one thing, it would be this: your brain is not broken. It is not failing you. It is doing exactly what it was designed to do in a world that was never designed for it.

And today’s conversation is going to change how you think about it. Clear some space, go for a walk, and put this on.

Love SA x

🎧 Listen to Live Well Be Well
How To Stop Overthinking Things You Can’t Control With Dr Hannah Critchlow

Here’s what we explore together:

00:00:00 Intro

00:04:08 Why Our Brains Fear Uncertainty More Than Pain

00:16:01 How to Build Habits That Protect Your Brain

00:21:00 Hannah’s Personal Story: PhD Burnout and Starting Over

00:28:00 What Happens to Your Brain During a Breakup

00:35:13 How to Move Forward After Loss or Grief

00:37:46 Sleep, Nutrition and Movement: The Brain’s Three Pillars

00:43:09 Essential Amino Acids and Why You Can’t Sleep at Night

00:46:05 What Emotional Intelligence Really Is (And Why It Beats IQ)

00:49:41 How to Train Empathy: Self-Compassion and Reading Fiction

00:52:27 Brain Synchronicity: The Science of Human Connection

00:56:13 Gut Feelings, the Vagus Nerve and Intuition

00:59:25 How a Healthy Gut Makes You More Altruistic

01:00:15 Emotional Regulation: What to Do When You Can’t Switch Off

01:05:26 Why Alcohol Makes Emotional Regulation Worse 0

1:08:58 How We All See the World Differently: The Duck, The Rabbit and The Dress

01:15:44 Loneliness, Mitochondrial Health and the Cost of Disconnection

01:17:01 AI, Human Connection and What We Risk Losing

01:38:50 What the Pandemic Taught Us About Face-to-Face Connection

01:41:24 Why Collective Intelligence Is Our Greatest Superpower

01:42:07 What “Live Well Be Well” Means to Dr. Hannah Critchlow

Check Out My New Book: Sunday Times Best Seller, Healthy Shouldn’t Be This Hard

June 8th: The Science of Self-Compassion & Lasting Health.

Come and join me for an evening with Seed Talks at 21 Soho.
Doors open at 7 pm, talk starts at 7:30 pm - come down early to grab a good seat!

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My Key Takeaways below 👇

1. Most of us would rather take the electric shock than wait for it

A researcher at UCL gave volunteers a choice: sit with a 50% chance of receiving an electric shock, or just take it now and know it’s done. The vast majority chose the shock, just to end the uncertainty.

I think about how many of us do this in our own lives, rushing into decisions, numbing out, keeping ourselves frantically busy, not because we want to, but because sitting with not knowing feels unbearable. The discomfort of uncertainty is often worse than whatever we’re afraid of. That’s just how our brains are wired. And knowing that is the beginning of doing something different.

2. Overriding isn't coping, and your body is keeping score

The chronic, practised suppression of every signal your body sends you — push through, stay positive, optimise harder until eventually the system can’t hold.

What she described maps directly onto what I see in the science. When we live in a persistent state of stress and self-criticism, cortisol floods the body. Over time, this doesn’t just affect your mood — it disrupts digestion, weakens the immune system, increases the risk of chronic disease, and dysregulates the very hunger and fullness signals you’ve been trying to manage with another diet. Your nervous system shifts into survival mode. In survival mode, the brain doesn’t prioritise your health goals. It prioritises getting through.

What makes this so insidious is that overriding can look like discipline from the outside. It can feel like strength. But the research is clear: chronic self-criticism and the relentless pressure to do more keep the nervous system in a state of threat. And a body in threat cannot heal, regulate or restore itself, no matter how clean the diet or rigorous the routine.

If you’ve ever kept going when everything in you was saying stop, this is for you. Overriding isn’t strength. It’s a pattern. And it always has a cost.

3. Grief is losing an external hard drive

Heartbreak is the most listened-to episode on Live Well Be Well. And I think that tells us something important, not just about how universal this experience is, but about how little we actually understand what’s happening inside us when it occurs.

Because the brain doesn’t do well with uncertainty, and a breakup can bring a particular kind of uncertainty that creeps into the corners of your life in ways you don’t always expect.

What Hannah explained is that when a relationship ends, you don’t just lose the person. You lose a transactive memory bank, all the cognitive processing you had been doing together. Who remembers the social plans? Who holds certain parts of your world together. Suddenly, you have to do all of that alone, and your brain genuinely struggles with the extra load.

This is why the exhaustion after heartbreak can feel so out of proportion to what people around you think it should. It isn’t just emotional. It’s neurological. Your brain is rebuilding an entire operating system from scratch. And that, I think, is worth being far more gentle with yourself about than most of us ever are.

4. Connection is electrical, not just emotional

When two people are truly in sync, communicating openly, learning from each other, and genuinely present, their brainwaves begin to literally align. Hannah calls this brain synchronicity, and the research behind it is extraordinary. You can use it to predict how well a group will problem-solve together. You can even identify who the natural leader of a group will be within 30 seconds of them starting to work together, based purely on whose brain is synchronising most readily with those around them.

Medical students in America are now required to study humanities and read fiction specifically to exercise emotional intelligence and empathy, because immersing yourself in someone else's character and going on a journey with them trains the brain to understand perspectives other than your own.

5. Emotional intelligence predicts success more than IQ

This is the finding that I wish were taught in every school. Emotional intelligence — your ability to understand your own emotional state, regulate it, and genuinely attune to how other people are feeling — is the number one predictor of life satisfaction. More than academic intelligence. More than talent. And crucially, unlike IQ, it can be trained.

We’ve spent decades telling people to be smarter, work harder, know more. What if we’d spent that time helping people feel more? We don’t talk about emotional intelligence enough; in my opinion, it’s such a skill to master.

6. Your brain has a built-in reset button, and it’s outside your front door

When you walk in nature without your phone, your brain begins to produce what are called alpha waves. These are slow, rhythmic electrical oscillations directly associated with calm, clear thinking. The kind of mental state where you can actually hear yourself think, where creative solutions surface that were completely invisible when you were sitting at your desk staring at the problem.

Hannah explained that this state of gentle, undirected mind wandering, which she says we spend somewhere between 25 and 50 per cent of our day doing, acts as an incubator for ideas. It’s where your brain consolidates, connects and creates. The moments in the shower, on the walk, staring out of the window those aren’t distractions from the work.

This can be hard to grasp in the hustle culture many of us live in, and even for me, writing this newsletter as a very few intense weeks of book promo, I think we need this more than ever. Space for ourselves and our minds.

7.

Do you remember that image that went viral a few years ago, the one where some people saw a duck, some people saw a rabbit, and some people could flip between the two almost instantly? It turns out that the image isn't just a fun optical illusion. It's actually telling us something quite profound about how each of us constructs our own reality.

Because it turns out that the image isn't just a fun optical illusion. It's actually telling us something quite profound about how each of us constructs our own reality.

Your brain is not a camera. It doesn't record the world objectively and play it back to you. It builds a prism of perception from every experience you've ever had, every message you've absorbed, every story you've been told about who you are and what you're capable of. And then it uses that prism to interpret everything that comes after. Which means that what feels like absolute truth, the way you see yourself, your body, your worth, your capacity to change, is actually a perception. Built from a particular set of experiences, viewed through a particular lens.

Hannah says that people who can flip between the two quickly tend to be more creative and better at tolerating ambiguity and uncertainty. Their brain doesn't feel threatened by uncertainty; it stays open, flexible, curious.

8. Who you spend time with is a health decision.

The people around you are directly affecting your cellular energy, your mitochondrial function, and your capacity to feel well.

Researchers gave one group prebiotics and probiotics and left the other without. Those with the healthier gut microbiome, sending positive signals up to the brain, were measurably more altruistic and less selfish with strangers they had no emotional investment in whatsoever.

Then separately, studies show that when you feel stressed, sad or lonely, mitochondrial health (the energy-producing powerhouses inside every cell) declines within days, and when you feel genuinely connected, it improves.

Hannah’s framing was that we don’t just connect emotionally with other people. We connect biologically. Your mitochondria are responding to your relationships.

But she also says something really interesting: she’s not entirely sure which way the relationship runs. Does feeling connected improve mitochondrial health, or do healthy mitochondria make you more able to connect? The science suggests it goes both ways.

9. AI is not destroying your brain, but how you use it matters

You may have seen the headline that went around the world a while ago. A study appeared to show brain scans of someone using ChatGPT alongside someone writing an essay by hand. The ChatGPT user showed almost no brain activity. The person writing by hand had a brain lit up with activity. The conclusion the press ran with was essentially: AI is making us stupid.

Hannah said this can be very misleading, aside from the study being a small group of participants, the group that had been using ChatGPT was then asked to suddenly switch to pen and paper for their final trial. Of course, their brains showed less activity. Not because AI had damaged them. But because they hadn't practised that particular skill in the same way. You don't get worse at something because of AI. You get worse at something because you stopped doing it.

When calculators arrived in classrooms, everyone panicked that mathematics was finished. What actually happened was that the education system raised the bar. Students were given more complex problems to solve because the basic arithmetic was handled. Mathematical ability didn’t erode. It evolved. She believes the same thing will happen with AI.

Use AI. Use it well. But don't outsource the thinking that makes you human, and keep your critical thinking!

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Big love, SA x