I went through a similar thing with a sprained knee (due to pandemic-related inactivity and resulting obesity). I had squatted down to pick something up, and when I got back up my knee, dodgy for years, finally said FU. I was still able to walk, but just barely, and I had to help myself get up out of chairs.
I started walking as much as I could stand, and after a long while, the knee improved dramatically. Then I noticed I was also losing weight even though my diet hadn't really changed. After a long enough time of this, I was able to once again put bike rides into the mix, weather permitting.
Daily walks (or equivalent/better exercise like bike rides or snow shoveling) have become part of my routine. I'm down 60 pounds from 2022, and at my best weight in over 20 years.