What Causes Leg And Foot Pain With Numbness?

I have recently had an MRI due to severe pain in my right leg and numbness that travels up my right foot and leg. It is constant numbness and will I can feel a touch its not a promenant feeling its like I can feel some but not all. I go to a neurosurgeon Tuesday but was wondering if there is any type of cardio that I can do as I have been on a diet for 11 weeks and need to workout.