The science of growing young (neoteny) underpins this book about maintaining or rediscovering ten youthful traits in ourselves as we age. The traits are resilience, optimism, wonder, curiosity, joy, humor, musicality (song and dance), work, play, and learning. Across all, there is love. The reader is encouraged to keep a Young Twice Chronicle for recording thoughts and outcomes as the book suggests do-overs and other activities for growing young-from the inside out.