A fascinating January 2020 study by Technische Universitat Dresden found that, “… completed intentions are sometimes not deactivated immediately, but continue to affect people. For instance, when implementing new intentions."
It appears that when completing a task that has been long delayed, the brain occasionally does not deactivate.
The researchers said, “Often, intentions seem to be deactivated as soon as they are completed … However, this deactivation does not always work perfectly like switching the light on and off. In some cases, connections between a stimulus and a completed action have to be dissolved step by step until the event or stimulus no longer trigger the retrieval of the completed intention."
As part of a broader health strategy, it would be interesting to design goals that utilize this feature (bug?) in the system. Perhaps we could add items to our “to-do” list that it would be useful to keep activated in the brain, even when they have been done.