Imagination is unique to humans (more than reason) and it is a blessing as much as a burden. The unfocused mind is filled with noise, and most of that noise is alternate timelines, paths not taken, what the OP calls "optionality". Meditation is the only thing that helps - relentlessly be in the present moment, on your cushion, taking a breath. The present is the only time in which you're getting actually new information - memory is rehashing old input, and imagination is anticipating new input.