If daydreaming counted as exercise, I would have no need of diet plans or gym memberships, and I would be quite fit, thank you very much!
I enjoy these short excursions into fantasy or nostalgia. Are they any different from delusions that comfort? My mother in her last years loved to tell about how she had walked the fifteen miles to visit my brother and her grandsons; all the while she remained in her room at the care facility. There was no arguing with her. She knew it was difficult, but believed she had indeed accomplished this. Maybe the advantage to the delusion is that you don’t have to come back to reality.
In my daydreams I go back to places I've been like the Bay of Naples or the deserts of New Mexico, and the advantage of doing all this traveling in a reverie is that you don't have to pack, or worry about the TSA, or finding your luggage on the carousel, and it’s free! It's off to faraway places in just the flash of a memory, and then in another flash you're off somewhere else.
Daydreams summon back mother, father, grandparents, and friends whom I can no longer see with waking eyes, and I can go back to happy memories over and over again like playing on the swings in the rain with my roommate Pat, tasting my grandmother's vanilla pudding with orange slices, or watching the stars fly off the grinding wheel as I stood next to my father at his tool bench.
Maybe I'm in denial of the sharp intrusions of reality, and even if it doesn’t take the place of physical exercise, daydreaming will remain part of my regimen,.