This cover image released by Avery Books shows "Practical Optimism: The Art, Science, and Practice of Exceptional Well-Being" by Sue Varma, MD. (Avery via AP)
Hayami Koga, a postdoctoral research fellow at the Harvard Center for Population and Development Studies, poses for a portrait in Cambridge, Mass., on May 23, 2023. (Kaoru Gleissner via AP)
Prince Bhojwani sits on Charlies Bunion mountain along the Appalachian Trail in Great Smoky Mountains National Park in Tennessee on April 17, 2022. (Nita Bhojwani via AP)
Hayami Koga, a postdoctoral research fellow at the Harvard Center for Population and Development Studies, poses for a portrait in Cambridge, Mass., on May 23, 2023. (Kaoru Gleissner via AP)