GoKawiilI spent the last month building a power meter for sledgehammer strikes: a pad you hit that tells you how hard you hit it, and whether you can do it again tomorrow.
This is the founder story: what I built, why I chose it, and what a month of hardware taught me. The engineering writeup will come later, once I've talked to someone who actually understands IP strategy. For now, the public home for the project is https://intensity.systems/ — sign up there if you want to follow along.
Why I used my sabbatical on this
After five years at Shopify, employees get a paid month off to do whatever the hell they want. I took mine in April 2026. Thanks Tobi!
I've been telling myself — and anyone who'd listen — for about six years now that I'd eventually end up doing something entrepreneurial. I've made small runs at independent things before: a band I toured with for two years in my twenties, a few abandoned company ideas, and during the pandemic a small gig selling weightlifting equipment out of my basement. That last one actually worked and taught me more about sourcing, logistics, and customer service than any job has. But I've never taken a dedicated, concentrated swing at an idea on my own time.
So I gave myself a rule: 20 working days, one idea, push on it hard enough to find out if it has legs. I have a folder with a dozen ideas in it, most of them software, many of them some version of "a better mousetrap." I picked this one because it was the one where I'd be forced to learn the most new things: hardware, enclosure design, product marketing, customer development... and because it felt doable in a month. Barely.
The gap I kept staring at
If you spend enough time around functional fitness, you notice that some modalities are beautifully instrumented and some are basically raw.
Running has pace, splits, heart rate, GPS. Cycling has power meters and an entire vocabulary for thinking clearly about effort. Rowing and the ski erg aren't exactly underserved either. Lifting gives you known loads moving through known distances; with a stopwatch and a notebook, you can at least estimate work and power.
Then there's the other category. Loud, messy, explosive, and weirdly hard to measure. Striking with a sledgehammer is the cleanest example, but it's part of a broader movement pattern — core flexion, driving a load downward with your whole body. Chopping wood, driving a stake, even the tiny domestic version of snapping a stubborn ketchup bottle downward. It's a fundamental human movement, yet in modern gyms I think it's criminally under-programmed. Very few people train it seriously. My hypothesis is simple: if a movement isn't measurable, it rarely becomes programmable. I set out to change that.
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