What is better, heating a room or heating yourself? When you are thinking on the last option, I have a very simple method. You can use a 12-volt electric blanket. The only thing you need to do is to make a slit in the center of the blanket to put your head through, and sew a collar around the hole with a strip of contrasting cloth. Take care with the direction of the heating wires inside the blanket. To close both sides, use Velcro. You can carry the battery in a small backpack. With a 12-volt lead (gel) battery of 12AH you can be warm for some time depending on the heating level you set.
The most simple electric gear hack, ever.
See drawings for details.
In all it’s glory!