Compare two quarters honestly. Same hours, same intent, roughly the same quality of work. One produced almost nothing and the other went well enough that people asked what you had changed.
You had not changed anything. That is what makes it uncomfortable, and it is why most people quietly conclude the difference was them.
The default explanation is wrong
The usual account is motivation. You were sharper, more focused, better at execution.
That does not survive much inspection. In the bad quarter you were usually working harder, because things were not moving and you compensated with effort. If motivation were the variable, the harder quarter would have produced more.
The more honest account is that effort does not convert to outcome at a constant rate, and the conversion rate is affected by things that have nothing to do with how much you want it.
What is actually varying
Some of it is external and obvious once you look — market conditions, a competitor's move, the season your customers buy in. Worth mapping before you look anywhere else, because a lot of apparent personal variation is really just your industry's calendar.
Some of it is the state you were in. Not mood exactly. The kind of work you were suited to at the time. There are periods where the outward push comes easily and periods where the same activity feels like pushing a car. In the second kind, the work that goes well is the building, fixing and deciding — but that is not usually what is scheduled, because the schedule was set by dividing the year into four.
The mismatch between the work in the month and the work the month could carry is, in my experience, the single most under-examined cause of a bad quarter.
Why this is not fatalism
Two things follow, and neither is passive.
You stop misattributing. A leader who reads a difficult period as evidence of personal inadequacy makes worse decisions than one who reads it as conditions. The first often restructures something that did not need restructuring, or fires someone who was fine.
You change the kind of work, not the amount. Difficult periods are where the compounding, unglamorous work belongs — the system rebuild, the documentation, the thinking that makes the next push cheap. Same effort, better placed.
How to see your own pattern
Take two years, month by month. Mark when things started well, when things fell over, when you were ill, and when you made a decision you later regretted.
Twenty minutes. Most people find something. Be sceptical with it — two years is a small sample and one bad November is not a pattern. Where the evidence is thin, hold it loosely.
Then look forward and ask a different question about next year. Not what the targets are, but what kind of work belongs in each period, and whether the big outward push is currently scheduled somewhere that can carry it.
Where the general answer stops
Your own record tells you what has happened. It does not tell you what is coming, and two years of data is not much to plan on.
There is a second read available — a mapped view of the conditions ahead rather than behind — and its value is not that it is more accurate than your own record. It is that you can compare two independently-derived pictures. Where they agree, you have something worth planning around. Where they disagree, trust your record, because it is your data.
That comparison is the useful move, and it needs both halves.