The different parts of a body work selflessly to serve one another and keep the body healthy. Similarly, a healthy society is one in which the different sections serve each other instead of selfishly trying to enjoy by themselves.
The more we make advancement in spirituality, the more we need to strengthen our service attitude, in order to bear the weight.
If one renders even a small amount of sincere devotional service, Krishna becomes obliged to elevate such a person and what to speak of one whose entire life and soul has been dedicated to Krishna's service.
When we become advanced, we recognize the service of other devotees and we develop our appreciation for them and it manifests in the form of friendship.