Warm blooded creatures, such as every human, must generate our own heat. I don't mean we plug in a heater or turn up the thermostat - it is our own bodies which create the heat, as we greedily shovel food into our mouths!
It's known as kinetic energy.

Failure to generate enough warmth results in frostbite, a potentially fatal condition in which your fingers and toes evaporate.

The 'normal' body temperature is around 37 degrees Celsius - apparently this is the same temperature at which chocolate melts!

Chocolate based lifeforms should therefore best steer well clear of Will Preston, whose body temperature is on average a WOW-tastic 45 degrees Celsius!