What began as a personal pick-me-up quickly became a feel-good phenomenon, tapping into the power of gratitude. In October 2011, Kubitsky began asking, "What makes you grateful?" and invited people to write or draw a glimmer of gladness on a postcard and mail it back to her. Placing blank invitation cards in public places like college cafeterias, post offices, parks, community centers, libraries, and cafes, she attempted to engage the community at...