Your body will be the primary indicator of whether you are overdoing your running. And you don't have to wait until you get a runner's knee, Achilles tendonitis, or a stress fracture to reduce your mileage.
Running excessively can result in overtraining syndrome, and you’ll know by experiencing symptoms like mileage reduction, tiredness, sleeping difficulty, pains and aches, inadequate motivation, etc. Take a break from running if you notice any of these signs and symptoms. If you develop a running injury, you should also stop running.