Taking Responsibility and Embracing Emuna

When something needs doing, it is easy to wait for someone else to step up first. Why should it be me? The Tosefta in Berachos says that at the splitting of the sea, the tribes argued over who would go into the water first, and that this is why Yehudah earned the kingship.Was it only a leap of emunah, or did taking responsibility itself change them? A Yerushalmi in Bikurim, about a chasan and a pasuk about Esav, points the same way, and asks what taking responsibility does to the one who takes it.