First I would refer them to a physician for physical activity release form. Proper health risks taken into consideration, I would start with low level activities like walking if capable, or swimming if obese. If they are not able to walk or legs are weak, possibly start with chair exercises. Increase leg strength with exerbands or leg weights. Upper cardio strength with arms movements, after a while use 3-5 lbs. free weights. Exercise would be 5-6 times per week at 30 minute intervals.