With so many hours of the day about just watching where to put your foot next, the alone time is reflection time. Around camp, we'd talk about the surprises of the Trail: how much more difficult the hike is on the body than we expected. Many of us considered ourselves fairly athletic before the hike, but NOTHING trains like the Trail.
The social climate on trail was another surprise. It certainly started out crowded, with overflow capacity for many shelters, which bad weather amplifies. All of the personality differences either jive or grate.
And the combination of physical and emotional strains play havoc with the mental condition. Without the distractions of modern life, one's inner voice gets to be heard. Some hikers I've known since Georgia have talked themselves off trail, some are pushing hard to not succumb to self-doubts of 'why I'm out here'. Second-guessing amid the mud or the dry, the monotonous meals, the sweat or the cold, missing family and friends. The voices in the head may be the biggest challenge.
Unless you're Doc's wife. They started in Springer. Who knew she was preggers -- so she's off trail while he picks up the pace to finish early. Now THAT's a motivation.