I agree, about the cold.
I have an attached garage and figured a way to warm my garage. It works fairly well except on the coldest days. It does raise the heat bill but at least I have been able to spend some time in my garage.
I opened the door to the garage and placed a window fan in the opening on the floor blowing the cold air into the house. Because of the design of the house I am able to direct it into the basement. I did it this way because it is easy and because cold air settles and is denser and easier to move. I then set the temp a couple degrees higher and turned the furnace fan on. After an hour or so my garage was tolerable, not like the tropics but I could work in it with some comfort.
If you do this you will want your furnace to be in good condition which it should be anyway. I also did not do it for long periods and certainly not overnight.