Excerise ideas for severe arthritic knees

Hi, I also have bad arthritic knees and find exercise difficult.
Walking a little but pain during it. I have bought a mobility cycle which I find helpful. The cycle is used sitting down so no weight on the knees and you can also use it for the arms.
Swimming is also good, however I don't do this because I am very big and would not want to wear a costume in public.
Don't over do it. A little often is better than a long session.
You can lose without much exercise but it may help in toning up.
I have lost 4 stone from July 2016 to November 2016 then from May 2017 to June 2017. Gave up during December 2016 to April 2016 and did put on nearly a stone.
Good luck to you.

Hand cycling is more difficult than you might think; I depended on it for about a year before I could use my feet enough for a regular bike again. I honestly think the hand cycle was a harder workout.

Swimming and/or water aerobics are great if you have those available to you.

There are a lot of seated upper body exercises you can do. They make up the bulk of my workout (I have arthritic feet/ankles, so I'm in a similar situation).

Gentle yoga may or may not be a good idea. I'd run that one by a doctor/PT first.

Ask your doctor for a referral to physical therapy and do exactly what they tell you. No one can accurately assess your situation and advise you without a physical examination. Good luck.