The child cries to have toys, but one who can cry for the Lord in love is certainly successful in the line of devotional service.
Devotional service to Krishna is the chief function of the living entity. There are different methods for the liberation of the conditioned soul Karma, jnana, yoga and Bhakti but all are dependent on bhakti. — Sri Caitanya Caritamrita, Madhya lila, 22.17.
Out of many millions of wandering living entities, one who is very fortunate gets an opportunity to associate with a bonafide spiritual master by the grace of Krishna. By the mercy of both Krishna and the spiritual masters, such a person receives the seed of the creeper of devotional service.
The human body is rarely achieved and although temporary like other bodies, it is meaningful because in human life one can perform devotional service. Even a slight amount of sincere devotional service can give one complete perfection.
It is true that by practicing restraint of the senses by the yoga system one can get relief from the disturbances of desire and lust, but this is not sufficient to give satisfaction to the soul, for this satisfaction is derived from devotional service to the Supreme Personality of Godhead. — Srimad Bhagavatam, 01.16.35.