You may have heard about Ayurveda, and the three Doshas. Ayurveda is the sister science of Yoga, you can read more about it here. According to Ayurveda everything consists of the 5 elements - Earth, Water, Fire, Air and Ether. In the human body, the combination of these elements are the 3 Doshas - Vata is air and ether, Pitta is fire and water and Kapha is earth and water.
When we are born, the same way as the color of our eyes is determined, our birth day and astrological sign is fixed, we also have an Ayurvedic constitution (Prakriti in Sanskrit) that is the percentage, or the set up, of the elements in us. This constitution does not change with time, it follows us through our lives. Knowing this constitution is beneficial for us, to know which element is already present in us in abundance thus can be easily imbalanced, and to know how to balance it by the diet we follow, the exercises we do, the lifestyle we lead.
Ayurvedic imbalance (Vikruti in Sanskrit) happens when one or more of the elements get aggravated, they are present in excess in the body and start to cause disease. When we know which element is out of balance we can focus on getting the balance back by applying the opposing quality to the aggravated element. A few examples of imbalances relating to the Doshas are bellow: