Purely personal!
In 2016 I started keeping a daily log of health. The first one started on Aug 6, so I’ve kept the same starting and ending date for each year.
In the first year the log only listed dumps and sleeps, plus an occasional note of an event that caused stress. Each day was one paragraph, three or four lines.
Each year the log grew longer and chattier, now mentioning EVERYTHING that happens, including details of weather and my usual dubious correlations and post-hocs.
Each year I found the previous year’s chat to be useful in verifying or disproving the correlations. Usually the SAME THING was happening on this date a year ago regardless of my alleged “causes”. The SAME THING is often described in nearly the same words. It’s all astrology.
As the back-reference grew more useful, I gradually added more detail to make the next back-reference better. Here’s a graph of file sizes.
Note that 2020 jumped beyond the curve for obvious reasons.
Polistra's Mill 