If you want to win in life, you need to solve problems. 

But as we level up, new and more complex ones emerge—ones our old way of thinking won’t solve.

The mistake most people make? 

We try to be smart. We assume that if they can just think harder, analyse more, or add more data, they’ll get to the right answer.

But complex problems don’t work like that. 

Not puzzles to be solved. Just systems to be understood.

And the best way to do that? Mental models.

Mental models help you see how systems work instead of just reacting to problems.

No book has influenced my thinking on this more than Thinking in Systems by Donella Meadows.

Here are three mental models from the book that changed how I approach decision-making—and how they can help you too.

1. Complex Systems Can’t Be Understood

In 2022, one conversation saved me millions.

I’ve always loved investing in public markets and was writing a tech investment newsletter called the Mopoke Cloud Index

Some people had followed along and wanted to invest with me. 

I reached out to a friend already deep in the game of managing other people’s money. 

He was going to pump me up. “You’ve got this, Andy!” 🙌

But instead? He hit me with a curveball. “Are you sure you want to do this?”

Huh?

"You're a business guy. If you want to build wealth, go build a real business.” He cautioned me on switching lanes and trying to beat the stock market. It’s not as simple as it looks!

And he was right.

Had I gone ahead with the fund? I would have lost money—mine and other people’s.

Because over the next 18 months, interest rates went 0% - 5%. 

The share price of many of those technology companies got crushed ~50%.

The stock market isn’t simple. It’s complex.

This is where Thinking in Systems really helped me understand the difference between simple, complicated, and complex systems:

• Simple problems → Making a cup of tea. You boil water, add a tea bag, done.
• Complicated problems → Sending a rocket to the moon. Lots of steps, but they’re repeatable with the right calculations.
• Complex problems → Investing in the stock market (or raising kids). No repeatable playbook exists because every action changes the system itself.

The first big idea - complex systems can’t be understood.

Interest rate hikes take months to impact inflation. By the time central banks react, they often overcorrect—leading to unintended consequences.

That’s why reacting too quickly to new information in a complex system can be a mistake. 

It’s better to think about probabilities - if we do X, what are the chances that this happens next? And then what?

The best decision-makers don’t just predict the next move - they are three to five moves ahead.

This applies to business, career, and relationships too.

We shouldn’t chase certainty—but rather different scenarios and probabilities to get the best possible outcome.

2. Shared Beliefs

In 2017, we were building our first startup with a small but dedicated team.

Grinding hard, but something was missing.

People were grinding through tasks, but there was no sense of purpose—no connection to something bigger.

We were so busy trying to survive as a company that we’d forgotten why we were even building this thing in the first place.

That’s where I learned the second big idea from Thinking in Systems. Shared ideas create the strongest systems.

You’ve heard the pyramids analogy on this. 

The Egyptians didn’t just stack stones for fun. They believed in the afterlife.

That belief aligned thousands of people around a shared goal.

It’s the same reason countries exist. Borders are imaginary, but because we believe in them as a society, we have passports, immigration laws, and national identities.

Back at my startup, we didn't notice the cracks.... until a nasty Glassdoor review made us realise we had failed at a very important thing.

Connecting everybody's work to something bigger. 

An advisor helped us craft the core vitals we needed (mission, vision, and values).

Everything changed. 

It aligned the team. Gave purpose to the work. Turned tasks into progress toward something meaningful.

As Donella Meadows explains, the most powerful way to change a system isn’t by tweaking its mechanics—it’s by shifting its underlying paradigm.

Changing paradigms is one of the most powerful leverage points.

Instead of adding more rules or policies to the company handbook, companies can shift their core mission. 

Imagine the difference between prioritizing 'an amazing workplace' vs. 'maximizing shareholder value'?

The lesson is if we’re trying to fix a system, don’t just push harder on the mechanics—look at the beliefs driving the behaviour.

3. Strength vs Agility

Alright, this one starts with video games.

Back in the day, I dabbled in online role player games like World of Warcraft. 

You could always tell the difference between the rookies and the pros by how they built their characters.

Rookies maxed out brute strength. Big weapons. Full armor. More power.

Pros focused on agility, movement, and adaptability.

And this is the same in business and life.

We want to be Spider-Man, not the Hulk.

The Hulk is strong, but predictable. Spider-Man wins by being agile, adapting fast, and thinking ahead—just like the best businesses and decision-makers.

One of the biggest insights from Thinking in Systems is that the most resilient systems aren’t the ones that resist change.

They are the ones that can adjust and evolve.

When we’re building a business, career, or skill set, can our systems adjust when things change?

The biggest risk isn’t the system breaking —it’s being so rigid that we can’t evolve.