The great souls achieve their greatness because of their unselfish motives. Such a great soul was King Yudhishthira, the eldest of pandavas. After kurukshetra war was over Lord Krishna advised Yudhishthira and his brothers to visit Pitamaha Bhishma, who was lying on a bed of arrows counting his last days. Pitamaha Bhishma, an ardent devotee of Lord Krishna, was the most experienced and the most knowledgeable person in kuru lineage. As per advise, Yudhishthira and his brothers approached Pitamah Bhishma and they had a long dialogue with him. In this dialogue Pitamah Bhishma touched upon many subjects in detail – how to run kingdom, what are the prime duties of king, how king should manage calamities etc. Yushishthira very attentively listened to all to what Pitamaha said. But even after listening to all his duties as king, he was not completely satisfied. Out of his unselfish motive of helping all his fellow citizens, he was curious to know about that activity that is supposed to be the most righteous of all righteous activities, by performing which every person whether a king or a common person, man or woman, will achieve - freedom from all sorrows, success in their prescribed duties, fulfillment of all desires and finally the most important goal of human life and that is moksha.
Pitamaha, very pleased with Yudhishthira’s curiosity, revealed to Yudhishthira that activity that is supposed to be the most effective and beneficial to all persons – and that is – remembering and glorifying Lord Vishnu all the time. And then he narrated to Yudhishthira 1000 names of Lord Vishnu, each name of which glorifies Lord Vishnu’s divine characteristics. All these 1000 names were compiled by Sage Vyasa and this collection of 1000 names came to be known as Vishnusahasranama. It has become so popular that whenever “sahasranaama” is referred it is considered as Vishnusahasranaama. There are such collections of 1000 names for other gods as well. For example Lalita sahasranaama (1000 names of Goddess Lalita), Shiva sahasranaama (1000 names of Lord Shiva) etc.
Navavidha Bhakti is a system of devotion devised by great Sages to help all fellow beings to get into devotion through nine steps. They say, out of these nine steps the steps that require most efforts are first three steps i.e. shravana (listening to glories of Lord Vishnu), kirtana (Singing the glories of Lord Vishnu) and Vishnu smarana (Remembering glories of Lord Vishnu). Vishnusahasranaama helps in all these steps. By repeatedly listening (shravana) to recital of Vishnusahasranaama (kirtana) one slowly gets into practice of singing the glory of Lord Vishnu (kirtana). And repeatedly performing listening and singing glory of Lord Vishnu one slowly gets into practice of remembering Lord Vishnu and his glories (Vishnu smarana) and when one is firmly established in remembering Lord Vishnu and his glories (Vishnu smarana), remaining steps happen as natural course of actions namely paada sevanam (resorting to lotus feet of Lord Vishnu), archanam (worshiping Lord Vishnu), vandanam (saluting Lord Vishnu), daasyam (devotional service to Lord Vishnu), sakhyam (divine friendship with Lord Vishnu) and atma-nivedanam (complete surrender to Lord Vishnu).
Chapter 4 of Dasbodh describes each step in detail.