If you aim at increasing the stamina, then it is in your hands. First of all it is important to know your power. For instance, you have the stamina of running on the treadmill for 5 minutes. Next time, you can try running for 7 minutes. Make sure that you are increasing the intensity on a gradual basis so that you don't feel tired. This also hold true in case of other exercises, increase the capacity slowly and your power will also increase.