Here’s an example. Our brains have networks known as the Default Mode Network (DMN) and the Task Positive Network (TPN).
Now, the interesting thing about these is that they can’t both operate at the same time. So, the DMN is our ‘resting’ brain state. (The clue is in the name!). This network roams the timeline, taking our imagination into the future and back to the past. This is all well and good if we’re experiencing positive or helpful emotions, when DMN can help us experience feelings like anticipation and warm nostalgia.
Of course, when our brain is already carrying an emotional load that tells us that we are under threat (such as a pandemic, or war in Europe… or even rising living costs), then that flips to a less positive outlook, and starts to lean towards rumination and worry.