Advil takes the edge off the muscle pain that eventually sets in on long rides. A cold drink from a convenience store - like a Coke - is a welcome stop. Stretch the calves/quads/shoulders while riding. I try to calculate how far to the next stop and an ETA to break the ride into smaller pieces.
On one particularly long ride by myself (from Kona to Volcano Village, Big Island), and no one else around, I sang hymns from Sunday school to keep my mind occupied, to the amusement of the wildlife and occasional passerby.