I also do the swimming and water exercises several times a week. I was told several years ago that I needed a knee replacement because my knee had deteriorated so badly from accidents over the years, and developed severe arthritis.
However, because of the a-fib and heart failure, the doctor said it was not safe to do this operation for me. He gave me a cortisone shot, and said it would help with the knee pain for somewhere between 3 months to a year.
While my knee was not hurting so bad, I watched videos for water exercises that help strengthen the knees and started doing that, and by the time that the cortisone shot wore off, I was walking much better, just from the knee exercises alone.
I will never be able to go on the long 3-4 mile walks like I have done most of my life, or easily go up or down stairs, but for most everything else, I am able to get around much better , and can at least walk better than before I started doing the exercises.
I think that everyone is right about it not helping for weight loss, but it does help build muscle, which helps a lot also. Combined with the OMAD, I am gradually getting more muscle and losing weight, although I mostly feel that i could live without eating at all and still not lose weight, it is such a slow process.
However, since I feel better, I persist.