When we first come to the path of Krishna Consciousness, Krishna, devotees, chanting, Kirtan, Prasadam, etc attracts our minds. We think "this is pure and fresh, I want to do this". We start our journey in earnest. Then as days go by, our enthusiasm starts to wane or plateau. Now, no more the same Krishna, devotees or chanting gives us the feeling it once did. Then the mind starts to wander during japa. The mind starts to see holes in others' services. The mind justifies judgement and self-righteousness etc etc. Certainly familiarity will start to breed contempt. Then, in just a matter of time the soul will wash back to the shores of maya by criticizing everything Krishna consciousness or at least the institutions' promoting it.
When we experience a lull, we have to understand that it is because of our desire for material enjoyment (in its myriad forms'). We also have to understand that our initial attraction to Krishna was actually not so pure after all but tainted with our enjoying tendencies. Therefore it is our job to clean our enjoying tendency. To let this tendency go unnoticed means we truly are not interested in Krishna but just in ourselves but in a different way (so called spiritualism).
Always, we have to be simple, honest and keep focus the purpose of spiritual life - that is - to love God without selfishness. As long as this selfishness is there we cannot truly appreciate the Bhagavat.
Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura mentions that...one must not desire material profit when rendering devotional service. Even if one follows all the sixty-four regulative principles, he cannot attain pure devotional service with a contaminated heart. - Purport by Srila Prabhupada CC Madhya 19.175