So how do your characters keep the faith when faced with seemingly unbeatable obstacles? What is it in their character that gives them the grit to keep going? How are your characters encouraged and supported? What motivates their friends to do this - genuine goodwill or have they got agendas of their own?
I've sometimes, when testing out a character, imagined them faced with this or that crisis and worked out how they would react. The test has succeeded when I can answer the point immediately. Character X would definitely react in this way because.... Not all of these pieces have made it into my stories but, for me, I need to know a character's dominant trait. And sometimes that only really comes out when said character faces crisis moments. Once I know for certain what that trait is, I'm up and running with that character and the story.