Finding your true calling can take years, even decades. Children’s book author Christopher Paul Curtis found his calling in his 40s. After spending more than a decade working at a Detroit car factory, he began writing young adult fiction about the African-American experience. He was the first American man to win the Newbery Medal literary prize. We talked with Christopher Paul Curtis ahead of his appearance Nov. 10 at 7 p.m. at Holy Trinity Parish Episcopal Church in Decatur.