My brain thinks I’m 20 too. I got a little happy adding some extra exercises to my weight training routine a couple months ago and my right forearm is still all jacked up.
A recumbent bike worked wonders for me. It’s easy, comfortable cardio. You can even catch up on movies/tv shows while doing it...lol
Not sure if it would work for you with your movement issues though.
Kudos to you for getting past the noise and getting the diet right. It’s so hard with so much misinformation out there. It’s almost like many doctors don’t want us to succeed.