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.
Working for Krishna is the ultimate perfection of all our activities.
The Krishna consciousness movement is therefore distributing sublime information to the entire human society to the effect that by simply chanting the Hare Krishna mantra one can become perfect in this life and go back home, back to Godhead.
Bhagavad Gita 9.25,
Srila Prabhupada
If by the tongue you chant Hare Krishna mantra and by the tongue you taste prasadam, you will be perfect, simply by executing these two things.
One should act according to the order of Krishna. This is very important point. That order of Krishna comes through disciplic succession from the bonafide spiritual master. Therefore, the spiritual master’s order should be taken as the prime duty of life. If one gets a bonafide spiritual master and acts according to his direction, then one’s perfection of life in Krishna consciousness is guaranteed. — Bhagavad Gita As It Is. 18.57.
One has to continue chanting the Hare Krishna mantra and preaching the chanting of this mantra because such preaching and chanting constitute the perfection of life.
Purport on Srimad Bhagavatam 4.24.67