So in what ways do your characters show perseverance? My Eileen and Hanastrew show a great deal of this quality, along with courage, in tackling foul fiends, dragons and so on. But Eileen is equally determined to keep on doing the right thing even if it does annoy her cousin, the Fairy Queen, and her Council. So Eileen persists, prior to her defection, with asking the kind of awkward questions she knows should be asked and will not back down from doing this. Courage and perseverance take many forms.
What are the consquences of your characters' perseverance? What happens to those characters who cannot carry on any longer and give up? Who is trying to get in your characters' way and why? Who finds the perseverance of others to be a threat, directly or otherwise? What do they do about it?
I can't think of any writer who can get away without perseverance as I think it is the only thing to help against rejections, negative criticism and so on. We need something to keep us going - and so do our characters.