During the hot weather, it can be easy to overheat.
Environmental temperatures of 40C (104F) can make it difficult to keep the body at its ideal 37C.
The advice - be sensible and slow down to stay cool.
While heat exhaustion is not usually serious, as long as you can cool yourself down, heatstroke is a medical emergency.
Here's what to look for and what to do.
Heatstroke or heat exhaustion?
Heat exhaustion happens when your body is becoming too hot and struggling to regulate or cope.
It can affect anyone, including fit and healthy people - especially if they are doing strenuous exercise in high temperatures or have been drinking alcohol in the sun all day. It can come on quickly, over minutes, or gradually, over hours.
The symptoms you will feel are your body's way of warning you to cool down, fast.
