Also knee injury, my surgeon told me no stress on the knee, no running period. I use isometrics and it helps. When I had surgery and was on crutches my friends told me oh that will slow down your coffee consumption....not at all just used a thermos to get it to the living room...lol
Hang in there. They have stuff now you wouldn't believe. I know it's tough not being able to just get up and do what you used to do, but you will find ways to deal with it. And hopefully it's not as bad as you think.
Don't let the pain and frustration get you down, and try to dwell on the good stories, not so much the bad ones. Just learn about it and be aware of what they are suggesting, and take that to your doc.
Water arobics are great, and I was surprised when my doc told me I could use my stationary bike. Be careful not to injure your good knee protecting the bad one. In other words, don't keep trying to do all you were able to do before your injury until you heal up.