According to Sanatan Dharma, the eternal and intrinsic nature of a living entity (atman), including Man, is to perform seva (service). Sanatan dharma, being transcendental, refers to the universal and axiomatic laws that are beyond our shifting belief systems. The Vedic literatures, which are the oldest scriptures in the world, give us some much-needed insight on this subject. The Vedic scriptures, that form the very basis of the tenets of Sanatan Dharma, conclude that a living entity achieves the perfection of his existence only when he dovetails his eternal nature in serving the Supreme Lord. Instead, if he chooses to serve his own senses or his false ego, then he encircles himself in a material quagmire that only makes him suffer in multiple ways. The service attitude that a soul (atma) possesses towards Supersoul (Paramatma), is not based on any obligation, but is instead built on a foundation of a loving relationship. The whole purpose of our existence is to render loving devotional service unto the Supreme Lord, recognizing Him to be our ever well-wisher and our eternal object of love.
