You don't need exercise to lose weight. Weight loss is mostly about our diet, so if you want to lose, you need to get that under control. Focus on getting lean protein, lean dairy, fruits and veggies. Keep processed foods to a minimum. Drink your water. Watch your caloric intake (especially if you can't exercise right now). Swimming is a great non-impact exercise that won't hurt your joints. You can check local Y and see if they have swim aeorbic classes. Do the best your can! You can do it!