Find something you have a streak going on. Anything. A language app, a step count, a habit tracker.
Now imagine losing it tonight. Not failing tomorrow, losing the whole thing, back to zero.
Notice what just happened in your chest. That feeling is disproportionate and you know it is. It is also, if you point it at the right thing, one of the most useful forces available to you.
The idea, named
Loss aversion. Daniel Kahneman and Amos Tversky, Prospect Theory, 1979.
The finding: people do not treat gains and losses as mirror images. A loss of a given size carries roughly twice the psychological weight of a gain of the same size. Not slightly more. Around double.
And the second half of the theory matters as much as the first. What counts as a gain or a loss depends entirely on your reference point, the spot you have mentally decided is zero. Move the reference point and the same outcome flips from a win to a loss without a single fact changing.
Kahneman, D., & Tversky, A. (1979). Prospect Theory: An Analysis of Decision under Risk. Econometrica, 47(2), 263 to 291. doi.org/10.2307/1914185

The asymmetry is not a bug in you. It is the most reliable thing about you. Build with it instead of apologising for it.
What this does to a streak
A streak is a machine for moving your reference point.
On day one, four hours of deep work is a gain. Nice if you get it, no real cost if you do not, because zero is still the baseline.
By day forty, the baseline has moved. Forty is now zero. Doing the work today is not a gain any more, it is maintenance. And skipping today is not a missed gain, it is a loss of forty days, which by the arithmetic of the theory lands about twice as hard as day forty-one could ever feel good.
Which is why streaks feel like they get easier and then abruptly become non-negotiable. Nothing about the work changed. The reference point moved, and now there is something to lose.

The honest note about Seinfeld
The popular version of this is the Seinfeld chain: get a wall calendar, put a red X on every day you write, do not break the chain.
Every retelling attributes it to Jerry Seinfeld. There is no primary source for it. He has never really confirmed it, and the story mostly traces to a single second-hand account that got repeated until it hardened.
I am telling you that because it is exactly the pattern this series is about. A good technique gets welded to a famous name, the name does the persuading, and nobody checks. The technique is fine. It rests on Kahneman and Tversky, which is real, and not on a comedian's calendar, which may never have existed.
Use the chain. Just do not cite the anecdote as though it were evidence.
The lineage, credited
Matthew Larsen's Work Form System is the direct parent of what I built: the 60-minute unit, the written record of every hour, the wall of documents, the small group that knows whether you showed up. Larsen is openly assembled from Hill, Maltz, Cardone, Hormozi, Jobs via O'Leary and Clear.
His step is the calendar, and the unit he chose is the one that makes this mechanism work properly: a day counts when four hours land in it. Not when you showed up. Not when you tried. Four hours, or the day is not a link.
That threshold is the entire design. A chain you can keep by doing nearly nothing stops moving your reference point, because there is nothing at stake in maintaining it. The bar has to be high enough that the streak is worth something, or it is decoration.
What we built
The chain lives on the Deep Mode dashboard. Consecutive four-hour days, a calendar strip, and the number set large.
WHERE THIS LIVES IN THE PRODUCT
Two design decisions, both of which are the mechanism rather than the presentation.
The threshold does not move. Four hours. Not three on a hard week. The moment a chain bends to accommodate you it stops being a thing you can lose, and a thing you cannot lose exerts no force at all.
The chain never nags you. No notification telling you the streak is in danger. That would be borrowing the mechanism to manufacture anxiety on a schedule that suits me rather than you, which is what most streak features actually are. It sits on a page. You go and look at it. Knowing it is there is enough, and if you want the reason why, that is the counter doing its own work.
This is Full Access, not the free plan. The free session gives you the room, the person and the timer. The chain is part of the measurement layer.
The uncomfortable part
You have quit things at day six, day nine, day eleven. Almost never at day fifty.
That is not because you became disciplined somewhere around day twenty. It is because early on there was nothing to lose yet, and the only real work in any streak is surviving long enough for the reference point to move.
So the first two weeks are the whole game, and they are the part where the mechanism is not helping you yet. Nothing makes those cheap. The one thing that makes them survivable is that somebody is expecting you at the tick, which is a different mechanism entirely and the reason the two ship together.

That's why I built this. I needed it. I have a chain going and I can tell you exactly how many days it is without looking, which tells you everything about how well this works.
Sources
- Kahneman, D., & Tversky, A. (1979). Prospect Theory: An Analysis of Decision under Risk. Econometrica, 47(2), 263-291. https://doi.org/10.2307/1914185
- Popularised as don't break the chain via Jerry Seinfeld. No primary source exists for the Seinfeld version; treat it as folklore, not evidence.