Not only can I imagine the beach, but sometimes I don't snap out of it until an hour (or more) later. At this point I have imagined an entire plot with myself as the main character and multiple other characters. The "movie" starts off at the imagined beach, including the bright sun making me squint, the feel of the sand under my feet, the smell of the salt water, etc. Next thing I know an hour (or more) has passed by. In this time I have befriended my fellow imaginary beach goers and joined them in defending the beach from a zombie invasion.

I had a similar experience to the author. Except that it was when I learned that not everyone experiences these intense fantasies. I experience a psychological concept known as Maladaptive Daydreaming. I find it difficult, and at times impossible, to stop visualizing through my minds eye.