For a native to have a sound constitution and robust health the Lagna and its lord should be strong and the lord of 6th should be weak. Sun is a natural aatmkaraka and gives health and energy. i.e. should be strong and free from malefic influence (especially from Saturn or Rahu) to give good health. Moon the planet of mind should also be freed from affliction for clear and sound thinking.
Those who have little knowledge of astrology are aware that 6th. The 8th and 12th houses are dusthanas. Malefics in these places are not good for health. The 6th house is of diseases and the 6th lord does give ill-health during its•dasabhukti. In the chart look for the planet in the sixth form Lagna and Moon, lord of the 6th house, and the sign containing the 6th house. These all combined together will give a clue about the disease and the part of the body affected by that disease. Besides these three trik houses, even the other houses if badly afflicted and containing planets badly afflicted give specific diseases governed by those houses, signs, and the planets contained in them. Such diseases are normally experienced during their dasabhukti of the afflicting planet(s) having sambandha with such a planet. The gochara of an afflicted planet is causative of the disease since a disease is caused when a planet is in an unfavorable position in gochara and its dasabhukti is running.