Patch, I think all you'd need to do to get your tone back is pushups, squats, and some type of bodyweight pulling motion. I'm not an expert or a trainer, but pushups are good for anyone to do. You can do them with your knees on the floor at first, if you have trouble doing them off of your hands and toes. Bodyweight squats are also a good exercise for any person, and it's fairly easy to add weight just by holding a heavy book or other object against your chest. Even a 5 or 10 pound dumbbell or a gallon jug of water will work. For pulling motions, if you have a bar of any kind that comfortably fits in your hands, find something about 3 feet high you can secure it to. (Like if you have some sturdy sawhorses in the garage, put them far enough apart you can lay down between them. Put the bar across them and somehow secure the bar so it can't roll off them. Grab the bar and lay back until you're hanging from it. Your heels should be on the ground and your body in a straight line from head to feet. Then pull your chest up to the bar using your arms and your back muscles, while keeping your body in a straight line. It takes some getting used to but it's really good for your arms, the back of your shoulders, and your latissimus muscles of your back. I think if you just did those 3 things every other day, you would feel stronger pretty quickly.
Don't feel bad if you can only do a couple reps of each at first. I can still only do a few of the rows. Even if you can just do one, keep doing it until you can do two!
For 100% BW I do 15-25 reps at one set wide grip and one set close grip.
