To repeat the message of God as it is is not easy or that straight forward. To repeat what the previous spiritual teachers and Krishna has spoken without taint of false ego requires a pure heart. We can memorize to a certain extent and repeat but if our repetition is based on memory then the message will be as it is only to the limits of our memory. Therefore repetition as it is in its proper sense has to come from realization of self and not memory of mind. To be self realized means to have a pure heart free from gross attachments such as material wealth, followers and family members and free from subtle attachments such as adoration, profit and distinction.
So when Srila Prabhupada says that we simply have to repeat as it is, implied in that is we have to become self realized before repeating otherwise our parrot like repetition will falter with time and eventually our message will be adulterated with our own false ego. Prabhupada stresses that we simply repeat as it is but that sort of unadulterated repetition requires us to be a pure medium of God. To cultivate purity requires desire, discipline and determination and above all the blessings of sadhu and Guru and Krishna.