When someone asks me "What's my life purpose?" I always ask them "What do you mean by life purpose?" They'll often reply"What work should I be doing?" referring to their career, which is indicated primarily by the 10th house. However, yesterday I mentioned that the 1st, 5th, and 9th houses are called 'dharma'houses and are the primary places to look for understanding our life purpose. Any planet associated with these houses, and/or their lords, will have a say in our life purpose, what we are born to do.
However, there's more. In Vedic astrology, we always look to the house, house lord, and the significator of a house to understand the condition of any particular house. For this reason, the Sun and Jupiter are important planets of dharma. They both are significators of the 9th house, while Jupiter takes on that role for the 5th house, and the Sun does the same for the 1st house. Between the two of them they cover all three dharma houses. Another angle on the issue is that Jupiter is the natural lord of the 9th house, being the ruler of Sagittarius, the 9th sign. The Sun, on the other hand, is the natural lord of the 5th house, being the ruler of Leo, the 5th sign. Anyway you look at it, these are the key players in understanding our dharma.
Isn't it interesting that the Sun represents our aspirations, while Jupiter denotes our inspirations. Both aspire and inspire come from the same latin root, 'spirare', which means 'to breathe' or 'to be filled with spirit.' To live our life purpose is not a luxury, it's our basic birth right, like breathing. When we're doing something that inspires us we feel the most alive, and connected to ourselves and to the Spirit that animates all life.