Five years after his first book , “Roar,” Michael Clinton is looking ahead. The author is releasing his second book , “Longevity Nation,” Tuesday, the culmination of his in-depth research into how living a centenarian life will impact travel, health care, career trajectories and more. For the book, Clinton interviewed 70 experts on longevity, prompted by the reaction to “Roar” and its subsequent consultancy, Roar Forward, which helps enterprises better connect with older consumers. “I was learning more about this huge movement around longevity, and I started meeting all these amazing people all over the world who were doing incredible work in medicine and technology and higher education,” said Clinton. “I realized they are the longevity innovators of our time, they’re the one writing the script.” Related Articles One of the things that compelled Clinton to write another book was the realization that most literature on longevity has been written by doctors.…