We spend approximately a third of our waking life mind wandering away from the present moment. New research shows that the healthy mind tends to imagine positive rather than negative aspects of the future when mind wandering. However, the presence of depression symptoms disrupts this positive bias during mind wandering. Critically, this depression-linked disruption was specific to imagining the future rather than remembering the past. Reductions in the tendency to imagine positive aspects of the future may indicate cognitive vulnerability to depression.

https://cbc.ca/life/wellness/it-s-ok-to-let-your-mind-wander-it-s-where-it-goes-that-makes-the-difference-science-says-1.4841722

https://link.springer.com/article/10.1007%2Fs00426-018-1071-y