Roger Owens, facing a "dark night of the soul" as he turned forty and entered midlife, was encouraged by his spiritual director to think of it instead as a "threshold of discovery." Rather than go on a grand adventure like walking the Appalachian Trail or the Camino de Santiago, he decided to mark his fortieth year by taking forty walks in a nearby nature preserve. With patience and attention, he explored the concerns rising with him: the inevitability of death, his boredom with life, and the reality of his changing faith, changing images of God, and changing sense of self. The result is forty short chapters that weave together insightful stories of his walks with accessible history and practices of Christian spirituality and the lives of saints. This field guide to the spirituality of midlife facilitates readers' personal journeys through questions of faith, purpose, and relationships. It is not solely a memoir, but a work of wisdom literature that uses engaging first-person narratives to explore universal themes and spiritual inquiry. Wise and imaginative, and with study questions for each section, Threshold of Discovery is the companion guide for a thoughtful Christian journey.