Can you do push ups? If so, sprinkle a little set of 5, 10, 20 (whatever is a light strain) through the day every couple of hours or so.
Pull ups and squats too as much as you’re able. Push ups give some core work, but some crunches or sit ups would be nice too. Core is key for strength and health.
Some form of cardio too, once a day 30mins. Just walking is fine.
This is what I used (on top of cutting sugary foods from my diet) to get from ~120kg to ~80kg and got compliments on my muscle building despite lifting no weights.
The constant light exercise is also great for mental health, giving a few chances a day for a little mental refresh.
I’m a big believer in calisthenics and just constantly living under the strain you want to be able to operate in. To me it’s the natural path, and I and a few friends had great success with this approach.
Lifting weights can give more efficient gains. If you can find a sport you like (swimming would be my top suggestion for someone with injuries to account for), the social pressure can be a huge help.
But what worked for me is simple constant light exercise. You can do it anywhere, and it gives a very practical strength and endurance that makes everyday life easier and more comfortable.
Just my two bits. Good luck
It can also work up to 150 years in the future, but you have to pay half your lifespan for the future eyes to really use it