Physical activity is important, not only to keep our muscles strong and our body fit, but also our joints supple and our state of mind positive.  However, overdoing exercise is detrimental to our health, too much will exhaust us and could potentially start a lupus flare.  The way to know what and how much exercise is right for you is your wellbeing.  Every one of us is different and we are also different every day.  My advice is have a regular rutine, one that works of an activity that you enjoy and then rearrange it according to the day.  
   I for instance enjoy yoga, walking and swimming.  If I know I’m going to be walking a lot one day, I don’t do anything else, for I can’t manage two physical activities a day.  If I have a more relaxed agenda and my body is cooperating, I go to a yoga class.  If the weather is good and I have access to a pool or the sea, that day I swim.  I try to do one of these things every day, but if my body says ‘no way', then I skip it altogether and try again the next day, no regrets!