It doesn't always happen right off, but eventually by following the conversion process a person starts having feelings. These are commonly described as a "burning in the bosom" or a "warm fuzzy feeling". They have to be told about the emotion, so they can recognize it and nurture it. Eventually, under certain situations, both private and social, these emotions will rise to the surface as a sort of "sign" or "witness to the heart" which can be relied on by "faith" or a hope that the emotions are signs from God, through the Holy Ghost. The early, or "primitive" as CJCLDS members say, Christian Church has accounts of this as well, as recorded in The Bible. Perhaps fixation upon these emotions can explain this earlier incarnation's rapid expansion as well.