First off, just looking at those pictures…Ouch. I hope they don’t hurt you OP.
Some suggestions I can think of:
Hiking if there are any places near you and you can get to them.
Woodworking? Not sure if you can do it because of your hands.
Gardening/Landscaping. I gardened this summer and while the effort was minimal since I didn’t plant much it was kind of rewarding. I’ve done a bit of landscaping (laying interlock) and it was also rewarding.
Running and/or swimming. Not exactly mentally stimulating I know but don’t discount the endorphin boost.
If you want you can try also asking this question at the !fitness community.