Cheerfulness is not a mood, Orison Swett Marden insists, but a power you can wield. He shows how a sunny, hopeful spirit heals the body, opens doors, and lightens every burden it touches, while gloom does the opposite. Full of vivid examples and gentle exhortation, it treats good cheer as a discipline worth practicing. A tonic of a book, and a reminder that how you meet the day is partly your own choice.