Hi TKala,

Please know that no matter one's weight or physical fitness, it is important to consult with your doctor before beginning an exercise regimen.  Only someone who know your health and personal situation can advise you on the safety and appropriateness of exercise, especially at high intensity level. 

I'm not a medical professional so I can't give medical advice and do not have the background nor training to know everything which might be involved in the risks of exercise for someone who is morbidly obese.

The things which do come to mind are an increased risk of cardiovascular problems if you have an underlying condition.  If you've never consulted a cardiologist or haven't undergone a stress test, that might be an important thing to do.  There could be a risk of injury to joints or muscles if exercises aren't conducted properly.  Someone trained, such as a physical therapist, would be able to advise on safe activities. 

This is not a complete list by any means.  But one activity which I've heard over and over is good no matter one's weight is walking.  If you don't have structural problems with your joints in the hips, knees, ankles, feet, then perhaps walking is a good place to start.

Listen to your body, when you feel that you need to rest.  Stop and rest!