Do as much as you can. Every step counts. If you're just starting out, start with 10 minutes a day and add more little by little. Work up to 10 minutes at a time, three times a day. You can also try for 15-minute spurts twice a day. Also if you don't have enough time to do a complete workout then you can just walk
You should at least eat healthy so you are still losing weight at a small pace but still doing it. Make sure you do work out though beacause it is really healthy for you.