Some of my villagers needed several childhoods to finally reach a level where they would honor on their own and start gaining skill. Once they were trained in everything else, I set them to Devotion and would grant Youth every time they reached age 14. After several times they had finally gained enough skill. Obviously, you need a Master Devotee teaching at the school, too.

Sometimes events will give them Devotion skill.
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Runners... never enough runners....