Need heating in my outdoor shed

My outdoor shed is an awesome place to workout. I have an multiple foot ceiling, twenty length and a twelve width in there. I have just enough space to kneel down multiple folding mats and be comfortable. Along the side I can tuck away my bicycle, speaker plan and jump rope. It is a cozy, cute little place to work out. I spruced it up by adding costly switch plates, bright aqua paint and a new light. It entirely looks care about a fun place to exercise. The only thing is that the shed isn’t properly insulated. The walls and ceiling have none and it shows. I added new windows that help somewhat, however are not a real fix. In the wintertime I have noticed that I entirely freeze to death. I try to wait to work out and I keep the door closed to retain my body heat. That only takes myself and others so far. I looked online at ductless mini splits and they are so extravagant. It would work perfect for my needs though. The indoor air handler would mount on the exterior wall and fasten to an air compressor outside. I would have a control equipment and the ability to heat or cool the space. I could even get a smart control equipment and beginning the Heating as well as A/C unit before I am in the building, and for right now I am looking at space heaters. They are so much cheaper and a quick fix. I don’t think it will be the magical cure I am looking for, however it will help in a jam.

Cooling corporation