Jayapataka Swami
As the materialists are thinking that happiness is all in sense gratification, they don't see the happiness in serving Krishna, that's where the real happiness is achieved in much higher relationship and higher purpose. Their thought is, "Alright Dharma, ardha, kama, moksha" now we will make money, enjoy our sense gratification and at the end of life go for moksha. Howvere in devotional service, we know about prema, the prema is actually the love for Krishna. It is the highest perfection and Krishna is the highest happiness also.
Bhaktisiddhanta Sarasvati Thakura
We should never display any kind of aversion towards sankirtana-yajna which is perfect sacrifice, complete with the seven forms of sacrifice. If we gradually increase our love for that, then everything will be accomplished and we will attain ultimate perfection. Just preach the words of Rupa Goswami and Raghunatha Goswami with enthusiasm, courage and complete dedication to the followers of Sri Rupa Goswami.
Subhag Swami
Prabhupada says, “Every night before going to sleep, read Krishna book, hear Krishna katha. If you are attached to this hearing, then by reading, reading, regularly, one day when you are going to sleep remembering all these things, may be in a dream, Krishna can come. This is perfection.
A.C. Bhaktivedanta Swami 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.