Your feet are constantly cold, wondering how to warm them? Make your own shoe insole. Most people throw a tetrapak made of milk or juice in the trash, and they are not even aware that it warms their feet up to -30C. Cut the tetrapak in the shape of a foot and place it under your insole on your shoes, boots or sandals. The sole will let the cold in much less and your feet and legs will warm more easily.