Developing faith is not easy. None of us is born with this trait in place, even if we are born into a religiously observant family. Each person has to work on his or her own to develop their relationship with G‑d.
Source:Worried All the Time
Is "this trait" refer to "developing faith?"
This suggests that it is just faith.Each person has to work on his or her own
(And what is 'not easy' is developing faith - that is, not having it and then coming to have it.