With something called fire
They both use heat to warm themselves.
They keep themselves warm by their clothings
To keep themselves warm. (insulation is taken from insulate)
a long time
By wearing warm clothes and by sitting infront of heater
They probably warmed themselves up with animal skins and also maybe keeping warm with fires
To warm up and stretch their muscles so as to not hurt themselves.
Bats, such as the brown eared bat, stay warm by sleeping with other bats and wrapping their wings around themselves
to keep warm day and night and to protect themselves
One can prevent the onset of hypothermia in cold temperatures by keeping warm. To keep warm, you need to wear lots of clothes or take shelter. Alternatively, you can become active to increase your body heat or you can use a fire to keep warm.
Turtles warm themselves by staying in the sun.
The best ways to keep food warm for a long time are using insulated containers, slow cookers, chafing dishes, and hot holding cabinets.