Why I built a device to interrupt myself

From a homemade timer to a foot-worn wearable — the story behind Stirr

In March 2020 I closed my laptop in an office for the last time and opened it again at home. Like a lot of people, I assumed the change would be temporary. By the end of that summer I'd set up an office in the small room next to the kitchen — handy for the next brew, useless for adding steps — and quietly stopped commuting altogether.

I'd also quietly stopped moving.

Not because I was lazy. If anything, I was working harder and concentrating for longer than before. There was no commute, no walking to meetings, no colleague appearing at the desk asking if I fancied a coffee. The little bits of movement that used to break up an office day had disappeared without me really noticing.

What I eventually noticed was how I felt by late afternoon. Sluggish. Stiff. Some days I realised I'd barely moved since breakfast.

I think a lot of remote workers will recognise this. Not the burnout or isolation side of home working — people have written plenty about that already. I mean something simpler: when you work from home, the day loses its built-in interruptions. You can end up sitting for hours because you're focused on something else.

I did what most techies do

I built an app.

There were already break-reminder tools and fitness apps around, and I'd tried some of them. A few were decent. But most seemed built around daily step counts or generic wellness goals, which didn't really address the problem I was experiencing. I could easily hit a step target with a long walk and still spend most of a Tuesday sitting almost continuously.

The honest truth is that I didn't do a detailed comparison of the alternatives. When a techie sees a problem, the instinct is usually to write code. So I wrote code.

The first version was a short guided movement session — two or three minutes at a time, a few exercises, a simple record of whether I'd done them. Nothing sophisticated. It was basically me trying to solve my own problem.

It didn't work. I was too busy to open it. Which is, of course, exactly the same reason I wasn't moving in the first place.

The fix wasn't a particularly imaginative leap: I added hourly prompts. Instead of waiting for me to remember, the app told me. That single change was transformative. I've been using some version of it almost every working day since.

That app became Microcise.

Microcise becomes Refreshed

Microcise worked well enough that I kept using it. Friends started asking if they could use it too. And once that happens, the questions become more interesting.

Why do some prompts work for some people and not others? Why do certain movement sessions feel restorative while others feel irritating? How long does something need to last before it actually helps?

Those questions pushed me toward behaviour-change research and eventually into the academic literature behind digital interventions. B=MAP from BJ Fogg. Self-determination theory. Habit formation. Implementation intentions. The frameworks that try to explain why people respond to prompts at some moments and completely ignore them at others.

That changed the direction of the project quite a bit. Microcise had mostly been built from instinct. Refreshed was the point where I started trying to ground the design in something more systematic.

The prompts became more adaptive. Sessions were adjusted to capability and context. The focus shifted away from chasing targets and toward building sustainable routines that fit into real working days.

At the same time, the project gradually turned into part of a doctoral research programme looking at whether these kinds of interventions genuinely work outside controlled lab settings.

But there was still a problem sitting underneath all of it.

The app could send prompts. It could track whether someone opened a session. It could record whether they completed one.

What it still couldn't reliably tell was whether they'd actually moved.

Like most digital wellness systems, it ultimately depended on self-report and app interaction as proxies for behaviour. And self-report is — politely — unreliable.

The device that closes the loop

That's where Stirr came from.

Stirr is a small foot-worn device that threads into your shoelaces and sits on the tongue of your shoe. Its job is very simple: detect movement accurately and quietly in the background.

It isn't trying to count steps, calories or sleep. That's not what it's for. It just answers a simpler question reliably: are you moving or not?

The foot turned out to be the best place to measure that. Wrist devices are dealing with constant noise — typing, drinking, moving your hands around during calls. A foot gives a much cleaner signal. If your foot is moving, there's a good chance you're actually getting up and changing position rather than just gesturing at a screen.

What Stirr adds is a proper feedback loop between the intervention and the behaviour itself.

The app delivers the prompt. The device verifies the response.

That means the system can eventually adapt based on what really happened rather than what someone remembered to log afterwards. If you've already moved, it can back off. If you've been stationary for hours, it can intervene differently. And over time it becomes possible to measure whether the interventions are genuinely helping rather than simply generating app engagement.

At that point it stopped feeling like "an app with reminders" and started feeling like a proper system.

The names evolved alongside that journey: Microcise became Refreshed, and eventually Stirr — now the name for both the device and the wider platform.

Why this matters

I would probably still have built this even if it only helped me personally. But the deeper I got into the research, the clearer it became that this isn't really an edge case.

The evidence around prolonged sedentary behaviour is now substantial. Long uninterrupted periods of sitting are associated with poorer glucose regulation, reduced insulin sensitivity and measurable vascular effects — even in people who exercise regularly.

The interventions don't have to be dramatic. In many cases we're talking about short interruptions to long periods of sitting. A few minutes of movement at the right time. The kind of movement office life used to force into the day naturally before remote work removed so much of it.

That's where this blog is heading next.

I've been experimenting with continuous glucose monitoring alongside the Stirr system to see what actually changes when movement becomes part of the working day again — particularly after meals. Some of the early experiments were messy and badly controlled. The newer ones are much more structured.

I'll share the results as I go.

What's next

If any of this sounds familiar — if your workdays have gradually become longer, flatter and more static than they used to be — you can subscribe below.

I'll be writing about the research, the experiments, the hardware, and what happens when you start treating movement not as a fitness goal but as part of the structure of a working day.

There's also a small founding cohort opening up for Stirr itself for people interested in trying the first production run. The initial batch will go into production once twenty people have registered interest.

Register interest in Stirr

I built this because I needed it myself. My suspicion is that a lot of other people probably do too.