Starting over

Hi my name is Debbie. Several years ago I lost 256 pounds. I regained about 100 over a couple of years. Two years ago I was diagnosed with a rare form of Breast Cancer. In addition I had suffered a spinal cord injury from a work accident that has left me permanently disabled. I beat the cancer and lost 60 pounds during treatment. Unfortunately I am unable to exercise very often and slowly gained back much of that 60. I just recently saw my oncologist for a check up and although I am still cancer free he told me obesity is the most common factor in reoccuences of cancer. I took him seriously and am making significant changes in my food habits. I need help finding exerciss I can do sitting down.