My question somehow relates to this question asking about how pilots cope with boredom, but now the scenario is not the typical airliner configuaration with two pilots, but with only one. I'm thinking of single pilot operated business jets with flights over, say, 4 hours. What does the single pilot do to prevent boredom and associated problems such as vigilance loss and fatigue? They've got no one to chat with as stated in the first answer to above cited question... of course, they will continue to check and monitor systems, occasionally report and talk to ATC, but there is plenty of scientific evidence (i.e. see this book) a simple monitoring task can easily lead to fatigue - so are there any methods pilots use to prevent boredom and vigilance decrement?
Not long ago, I had my longest flight as a PPL: about 4 hours from Dallas, TX to Kansas City, MO, in a 172, facing a steady headwind the whole way, so making a ground speed of less than 90kts.
I ran checklists about twice as often as normal, and re-did my fuel calculations very regularly (in part because of the extremely slow progress).
I listened to the ATC frequency, and tried to build a good mental picture of all the planes around me.
I went through every single setting and option on my MFD glass cockpit and iPad.
I watched the scenery, both for visual navigation (despite my GPS), and just to admire the view.
Even after all this, the flight was pretty boring near the end, and I'm glad I don't do flights that long very often.