I Have Had Arthroscopy On My Knees, I Go To

I have had arthroscopy on my knees, I go to the gym 3/4 times a week do gentle e xcercise bike, rowing
Stread mill and swim I also try to walk 3/4 times a week from 1/2 hr to 1 hr please can you advise me if I am doing more harm than good. I also work in retail twice a week and am on my feet for 8 1/4 hrs.
I really really appreciate any advise thank you