Are my levels too low

Not too much exercise, just probably not preparing for it. Not sure whether you're insulin dependant or not so can only offer limited advice but as a rule of thumb, do not attempt strenuous cardio if BS below 7. If you take insulin, lower dose prior to workout. If not, eat some fast acting carbs ( cereal bar ? ) prior to workout. Try to test your blood after exercise and act accordingly. Exercise is key to good health, adjust to the workout, not the other way around ;-)