I have read some accounts of people hiking in the mountains that border Tennessee and North Carolina or Virginia, that have succumbed to death from hypothermia. Accounts have stated that they wandered off the trail and we're lost. I read a book written by a tracker that said when they would wonder off the trail, and sometimes not very far, they would get disoriented because every thing looks the same, and the foliage to thick to find a small trail. The lost person would go in a direction they think correct, and would go further from the trail and make situation worse. After a couple of days of being damp, hungry, and lack of shelter a person can easily start to get hypothermia. When ever my wife or I have stepped off the trail for a little privacy, the other would stay put on the trail and the one that was off the trail did not wander to far.
If you lose track of the trail STOP as grandpa said. Carry a whistle. It's easy to lose the trail. Just because you can see civilization doesn't mean you can physically make it either.