The Heroin Experiment That Accidentally Explained How Habits Work

In May 1971, two US congressmen returned from a visit to Vietnam carrying news that detonated across America: heroin use was rampant among American soldiers — with studies later confirming that roughly one in five enlisted men had become addicted while deployed.

Panic followed. Heroin was considered the most enslaving substance known — the relapse rate (the percentage of recovered addicts who return to using) for addicts treated back home hovered around 90%. Now hundreds of thousands of trained soldiers were coming home, and the government braced for an epidemic of addiction flooding every town in the country. President Nixon declared drug abuse "public enemy number one" and commissioned an urgent research program to track the returning men.

I came across this study while researching habit formation for Thunder Motivation — and what the researcher found was so counterintuitive, so disruptive to everything we think we know about willpower and addiction and change, that I've been thinking about it ever since. Because the lesson isn't about heroin. It's about every habit you've ever tried to build or break — and why the approach you've been using is almost certainly wrong.

The Study That Nobody Believed

A researcher named Dr. Lee Robins at Washington University ran the study. And what she found was so unbelievable that much of the scientific establishment simply refused to accept it.

The addicted soldiers came home... and roughly 9 out of 10 of them just stopped. No rehab. No treatment. Only about 5% relapsed within the first year (Lee Robins' Vietnam veterans study — National Institutes of Health). The most addictive drug on the planet — dropped, en masse, like a subscription they forgot to cancel.

For decades this result was treated as a freak anomaly — an unexplainable blip in the data. It wasn't. It was the biggest clue we've ever been handed about how habits actually work — including yours, including mine, including the ones we're building and breaking right now.

The Secret Was Never Willpower

Here's what Robins' data revealed: the soldiers hadn't beaten heroin with iron will. They'd beaten it with an aeroplane.

In Vietnam, every cue — the environmental trigger that initiates a habitual behaviour — that triggered the craving was everywhere: the stress, the barracks, the fellow users, the constant availability, the sound and smell of that world. Then they flew home, and every single trigger vanished at once. New house, new faces, new routines, no supply on the corner. The craving had nothing left to grab onto.

Meanwhile, addicts who got clean in American rehab centres relapsed at catastrophic rates for the mirror-image reason: they got sober in a clinic, then walked straight back into the same street, same friends, same corner — the exact environment their addiction was wired to. The willpower was present. The environment overrode it.

The uncomfortable, liberating conclusion: a habit doesn't live inside your character. It lives inside your environment. Change the environment, and even heroin loosens its grip. Keep the environment, and even heroes relapse. This is the same principle that underpins our complete guide on how to rebuild focus from the ground up — your attention isn't weak; your environment is hostile.

Your Brain Runs on Loops

The mechanics are simple enough to draw on a napkin. Every habit — good or bad — runs on a three-part loop: cue → routine → reward. This framework was first articulated by researchers at MIT studying habit formation in rats and later popularised by Charles Duhigg in The Power of Habit.

A cue is just a trigger your brain has learned to notice — a time, a place, an emotion, a person, or a preceding action that sets the loop in motion. Let me make it personal: you sit on your bed after dinner (cue), your hand finds your phone before you've made any conscious decision at all (routine), and you get a little hit of novelty and relief (reward). Run that loop a few hundred times and it stops being a choice. It becomes automatic — as automatic as reaching for the steering wheel when you hear a horn.

Researcher Wendy Wood at USC has spent decades studying this process. Her research found that around 43% of your daily actions happen this way — on autopilot, in the same contexts, with no real decision involved (Wendy Wood's habit research — USC).

Read that number again. Nearly half your life isn't being decided. It's being replayed.

This is why New Year resolutions die by February. People try to overpower the routine — muscling through with willpower and motivation — while leaving every cue lovingly in place. Then they blame their character when the loop wins. That's like leaving a loaded gun on the table and being shocked when it fires. The loop isn't the problem. The cue is. This connects directly to why motivation disappears — you're fighting the wrong battle in the wrong location.

Be the Architect, Not the Soldier

You can't fly to a new country every time you want to change a habit. But you don't need to — you just need to move the cues. Small environmental edits punch absurdly far above their weight. BJ Fogg's research at Stanford's Behavior Design Lab has demonstrated that the most reliable way to change behaviour is not through willpower or knowledge, but through environmental design — making the correct action the easiest action and the incorrect action the hardest one.

Make bad cues invisible. Phone charging in another room at night — not on silent, not face-down, but physically absent. Apps deleted, not just closed. Junk food not "resisted" but simply absent from the house. Every cue you remove is a hundred battles you never have to fight. This is why our guide on minimalist focus apps emphasises tools that block and remove rather than tools that track and remind — removal beats monitoring every time.

Make good cues unmissable. Guitar on a stand, not in a case. Study book open on the desk at tonight's chapter. Running shoes by the door. Water bottle on your workspace. Let the room whisper the habit before your mind can debate it.

Attach new habits to old cues. Your existing routines are pre-installed triggers — reliable, automatic, already firing daily. After I pour my morning tea → I read two pages. After I close my laptop → I write tomorrow's one priority. After I sit down for dinner → I put my phone in the other room. You're not building from zero; you're piggybacking on loops that already fire daily. This technique, which Fogg calls "habit stacking," is the most efficient way to build the kind of success habits that actually stick.

Change your "Vietnam" when starting over. New chapter of life? Rearrange the physical layout — new desk position, new study spot, new route to work, new configuration of your room. A fresh environment gives old loops nothing to grab, exactly like that flight home did for the soldiers. If you've ever noticed that you're more productive on holiday, in a library, or in a coffee shop you've never visited — this is why. The old cues are absent. The old loops can't fire. Your willpower, for once, doesn't have to fight anything.

Audit the loops you're already running. Spend one day noticing, without judging, the automatic behaviours that happen around you. When I walk past the kitchen → I open the fridge. When I feel stressed → I open Instagram. When I finish one task → I check email before starting the next. Once you see the loop, you see the cue. Once you see the cue, you can move it. And moving a cue is infinitely easier than overpowering a habit.

The soldiers weren't stronger than the addiction. They were somewhere else than the addiction. Stop trying to be a stronger soldier in a rigged jungle. Redesign the jungle.

What This Means for Everything You're Building

The habit loop applies to everything — not just bad habits you're trying to break, but good habits you're trying to build. The person who successfully builds unbreakable discipline doesn't have more willpower than you. They've designed their environment so that the disciplined action is the path of least resistance. The morning routine that actually works isn't the one you force yourself through — it's the one you've designed to flow automatically from cue to cue, so that by 8AM you've already done the most important work of the day without ever consulting your motivation.

This is the connection between Robins' research and the lesson of Captain Scott and Amundsen: motivation-based effort (Scott's surging) is the habit equivalent of fighting the loop with willpower. Discipline-based systems (Amundsen's steady march) is the habit equivalent of redesigning the environment so the loop runs in your favour. One dies in the snow. The other comes home.