Vigilance. I’ve written about this before, but the mental effort of staying attentive, the stimulus overload and awe of a rich visual field e.g. a view from high up, looking down over a clearing-dotted forest, and you’ve been tasked to watch for orcs; staying glued to your scanner for any sign of a blip; looking for a hint of wreckage as you pass over the mountains in your Cessna.