Well then:
My buddy had recently taken up road bicycle racing and had basically no stamina. He went riding with a mutual friend who rode like 50 miles per day commuting, talking the whole time. Dragged newb out on the Old Spanish Trail loop, to Sonoita Hwy, then back.
Newb bonked on the way back, going down a hill that terminated in a curve...just kept going straight, no energy to turn. Other guy kept riding and talking for about 5 minutes before realizing he was alone.
Went back and pulled newb out of a 15'x20' patch of prickly pear. He was just laying there wishing for death. Finally made it the last few miles home, drank a Pepsi and was like new again.