So I have been thinking, Kaladin broke because of his believed failure to save everyone but still forcing himself to live (it is a lot more complicate than that) made him a Knights Radiant.
Shallan spoke the truths of events that damaged her so much that she purposely forgot them.
Dalinar opened himself up and realised the person he was was horrible but to become better he had to move forward.
Teft coming to terms with how much he hates himself and how he caused harm to others because of it.
So what about Lift, Renarin, Jasnah, Lopen and others? What broke them or in apparently Lopen's case, what opened their mind to the Knight Radiant spren?