One day’s number is weather. Six weeks of numbers is climate. Watch the trend.

A single reading contains far more noise than signal. Any one day is shaped by sleep, food, stress, and timing, none of which have much to do with the thing you are trying to measure, so acting on one data point means reacting mostly to randomness. Direction only becomes visible across a long enough stretch.

Record your numbers but evaluate them monthly, and look at the line rather than the last entry. Change one variable at a time and give it weeks. Judge the slope, not the point you happen to be standing on.