[censored], knee problems are a major pain. I also struggled with my knees due to my weight. Was 286 pounds. Down to 215 today. No more pain. Took me 4 years. Swimming is a great, no impact full body workout. I also started doing bodyweight training. There is a website globalbodyweight (I think) that got me started with these last few pounds.
Excersising out side really does help. Ni gym fees, fresh air. I feel the pain for you guys. Inside for to long and depression starts. The hardest part of getting out there is the first 2 weeks. But it is so worth it.
MonkeyBomb
Good luck with that knee and I know you will get back out there!