That is a huge challenge! Ideally you would want to talk to a physical therapist for options. There may be seated exercises you could do with a resistance band. Or, if you can use small hand and ankle weights, you might even be able to switch back and forth quickly on some light strength training to get your heart up enough for a cardio workout. For super safe range of motion type exercises, try searching for Feldenkrais videos.
Simple tasks and exercises can do great works. Start with something small an move forward. The most important part is to make that a habit you do every day.
You can excercise by writing your feelings/Emotions on parchment and think as it if you are reflecting as you always look deep into the mirror to find you positive self. Or you can motivate yourself to do some meditation.
It's a very difficult situation… I would search for low impact workout or I would go to a specilistic gym that will tailor the workout on my needs