Yes, doing too much cardio to soon can cause you to injure yourself and overtrain. If you injure yourself and overtrain, this can prevent you from reaching your goal. You need to determine your goal and then plan accordingly. If you are unsure how much cardio you need to perform based on your fitness level, consult a fitness professional so they can do a cardio assessment to determine where your fitness level is at. Once they get this information, they can create a cardio program that is safe and progressive so you can reach your goal in a safe manner.