The answer is: Wear light, breathable clothes to keep your body temperature lower.
Answer: Dehydration
Explanation:
Dehydration can be defined as the loss of fluid from the body. The loss is more than the intake. When the water content of the body is less then the other minerals of the body gets imbalanced.
Incase of severe dehydration there is a decreases in the weight of the person as the body starts burning fat.
The same happened in case of Joshua were running marathon made Joshua's body weak and dehydrated.
the body temp can fall continuously when you're exposed to extreme cold weather or wearing wet clothing for a long time. This soon can lead into some potential diseases and disorders like infection, insomnia, stress and sepsis.
Hope it helps!