Tired of temperature issues in shed, getting mini split ductless installed

I am going to need to get an HVAC installed in our outdoor shed, when I first purchased my place I figured the shed was nice to workout in.

So there was plywood on one wall.

Who cares if there is no insulation? So the windows were old, no big deal. Well in the winter time it was just awful with how cold it was. I eventually ripped down the walls and ceiling to add insulation. I upgraded the windows with brand new. I figured if the shed was airtight I could get away with no heating and a/c. Nope, I was still cold. I then tried to get by with a small area heater. In order to workout in the wintertime I needed to wear long pants, a blazer and gloves with the area furnace on. If I thought to preheat an hour before our workout, I could eventually take off the gloves and blazer. It wasn’t exactly warm in there though, once summer hit I knew that window A/C wouldn’t do the trick. I was tired of never being the right temperature. I finally just bit the bullet and called our local HVAC business. I told them to install a ductless mini split and charge what they wanted, but the initial cost was pretty darn high. The device is super high-priced, however the HVAC install rate wasn’t. I have thought about it this way too. If I had to pay to workout in a temperature controlled area everyday, how much would I pay? I thought I would be willing to pay around 10-15 a day, which would pay for the device in a little over a year. So that helps when I think about it that way.
Air conditioning professional