Two kinds of push

There's a Finnish word, sisu, that doesn't translate cleanly. The nearest English is something like fortitude — the capacity to keep going past the point where you thought you were done, to reach into a reserve you didn't know you had. Finns treat it as a kind of national inner strength. If you've ever finished something you had no business finishing, you've run on sisu.

We were drawn to it while building the coaching layer inside Theater, and then a piece of research stopped us. Because it turns out sisu isn't one thing. It's two.

The finding that changed how we think about drive

In 2022, a team of Finnish researchers led by Pentti Henttonen, Ilmari Määttänen, and Emilia Elisabet Lahti published the first attempt to actually measure sisu — the Maistro Scale — in the journal Heliyon. When they ran the numbers, the trait split cleanly into two separable forms.

One they called beneficial sisu: perseverance, an action mindset, a sense of holding power in reserve. In their data it tracked with better health, higher life satisfaction, and a stronger sense of accomplishment.

The other they called harmful sisu: pushing in ways that harm yourself, reasoning that's gotten distorted under strain, and pushing in ways that harm others. That one tracked with work stress and burnout.

Same engine. Two directions. A 2025 follow-up by Antikainen and colleagues in the International Journal of Wellbeing watched it play out in daily life — dozens of Finnish knowledge workers, sampled several times a day for three weeks — and saw the same split. On high-beneficial-sisu moments people reported determination, a feeling of control, and genuine positive emotion. On high-harmful-sisu moments they reported taking on tasks that were too big, getting stuck grinding on things that weren't moving, and more anxiety.

Why this became the spine of the coach

Most wellness-flavored productivity tools respond to that danger by trying to turn the intensity down. Take a break. Do less. Be gentle with yourself. And for a lot of people that advice is exactly wrong, because the intensity isn't the problem — it's the most valuable thing they've got. Told to dial it down, they just leave.

The sisu research pointed at a better job to do. Not reduce the push. Keep it pointed at the form that builds instead of the form that burns.

That's the whole idea behind how Theater works. In Theater, everything you're working on is a production — a real thing with a shape, an outcome, and an ending. And a production is intensity with an object. It's the difference between drive aimed at something you're making and drive that's just being spent. Harmful sisu is what happens when the pushing loses its object: lots of effort, no movement, the finish line quietly receding. Beneficial sisu is effort that closes distance.

So the coach's actual job isn't to cheer you on. Cheering the push is the one thing that makes harmful sisu worse. Its job is to notice, out loud, which kind of push you're running — because you can't feel it from the inside — and help you re-point it. We named it Maistro because that is the thing it's there to look after.

Concretely, that means Maistro watches for the tells the research describes, in the work itself: a scene you keep touching that hasn't moved a stage in two weeks (effort without traction — the tiring kind). Scope that keeps expanding while the finish line keeps sliding back. A burst of finishing everything and then going dark (a reserve spent to zero rather than held). When it sees the building kind, it gets out of your way. When it sees the burning kind, it doesn't scold and it doesn't tell you to stop — it shows you the pattern in your own work, points at the one action that would actually move the production, and reminds you that pausing cleanly is a move too. (Theater has a stage called Intermission for exactly that reason — a pause is not a failure.)

What we're not claiming

We think this research is a genuinely useful lens. We don't think it's a lab result you should bet your mental health on, and we'd rather tell you why than pretend.

Both of the studies above used Finnish samples only. Maistro is a Finnish cultural concept, and the two-form structure is, so far, an initial validation inside that one culture — it has not been confirmed to hold up elsewhere, and at least one recent critique has argued that turning sisu into a universal measurable trait strips away part of what it means. The 2025 daily-life study was small, had substantial missing data in some of its mood measures, and one of its subscales — the "harm to others" one — was statistically weak enough that the authors flagged it themselves. None of it establishes cause and effect; it's correlation.

So we don't use it to diagnose you, score you, or slap a burnout meter on your dashboard. That would be both bad science and exactly the shaming move we're trying to avoid. We use it the way you'd use a good map that's admittedly missing some streets: to help you see something about your own drive that's genuinely hard to see from where you're standing — and then to keep that drive aimed at the thing you're building.

Push hard. We just want to make sure it's the kind of push that leaves something standing.

Sources. Henttonen, P., Määttänen, I., Makkonen, E., Honka, A., Seppälä, V., Närväinen, J., Garcia-Velazquez, R., Airaksinen, J., Jokela, M., & Lahti, E. E. (2022). "A measure for assessment of beneficial and harmful fortitude: development and initial validation of the Maistro Scale." Heliyon, 8(11). · Antikainen et al. (2025). "Mental fortitude in everyday life: Associations between beneficial and harmful sisu, sisu-related states and affects, measured by ESM." International Journal of Wellbeing.