For the past thirteen or so years I did all my work outside, in unheated, unlit spaces. My primary workshop was my old 'greenhouse' as pictured below. It was not bad. Just really cold on cloudy fall and winter days. And usually wet, too, as the condensation would collect on the inside of the roof plastic, and any banging or wind would set it to falling, just like rain even on dry days. Bad enough.
Although I still have to go outside when I use my large saw, or to cut long lengths of copper, much of my work can now be happily done in my new workshop. It may not look like much, but for me it is absolutely fantastic.
Here is the old shop: