This is a tough thing to put in words, so Im not sure it is coming out
Kiruv will also only work if It can fit in the persons life and what I mean is, for example Kiruv is much tougher if the person is married to a non-jew or is forced to alter family relationships in a bad way.
Ive met people who experienced a Shabbos and felt inspired , but when they went home, they were isolated on Shabbos (They lived too far away from a shul and lived with non-religious people and were not always able to go away for Shabbos and could not move) It was doomed to fail