Retreats have a particular place in the life of a Buddhist practitioner. If one is fortunate enough to be able to join others to do that, all well and good. They are not essential and not to be clung to either. It is rare to have the opportunity to devote oneself to simply just sitting still without the usual daily life distractions. (Even so, life circumstances have a way of throwing up opportunities to sit, right in the midst of distractions. See comment from yesterday.) Having found the time, and settled down, the mind can spew forth, in all the weird and wonderful ways imaginable, each of us according to our own particular inheritance. Memories, thought patterns, emotions, sensations all march through body/mind. Nothing permanent, just passing though. However, when you are dying of thirst a lake in the desert can become all too real, and ultimately disappointing of course. A mirage certainly can appear real.
At the time of the Buddha's enlightenment the hordes of mara came to call shooting arrows, that fell around him as flowers. The Buddha unmoved, knew enough about the workings of the mind not to take False Evidence Appearing Real, as real. And that is what one learns, and re-confirms over and over again during a retreat. That is, to recognize fear for what it is, and refrain from being afraid of it. That fearful images and thoughts arise, or their equally alluring opposites, are not a problem. If not clung to as me and mine. As real. And yet moving on and out into everyday life, there may be good reason to be afraid, and to take note and to act accordingly.