The most exciting thing would be getting out of a chair. IT has hurt my body.
I do love creating things, though, so I would ideally be building original creations (I don't want to be a framer or service mechanic). So some kind of craftsman.
More realistically, I would create a business that could create value on-site, but dealt with customers on the internet. So ebay, etsy, etc. I understand building customer bases on the internet far better than I understand it in real life, and I also live in a low population area.
Most specifically, and ignoring income decreases, I would like to do some kind of old-timey craft. Woodwork, leatherwork, blacksmithing. Leatherwork in particular is quiet, relaxing, and doesn't need a particularly large area or set of tools, and I'm totally fascinated with handmade leather products. I would need a standing workbench, though!
I’ve done painting woodworking, soldering circuits , and ‘hacking’ some furniture, it feels great.