For all of its challenges, the opportunity to grow old is a privilege not afforded to everyone. Still, the true metric of success is not merely the length of our years, but the quality of our lives. Many scientists think we are approaching the biological limits of life extension, even as medicine advances our capacity to regenerate worn-out body parts and preserve mobility and multigenerational models of caregiving promote independent living. Can we shift our goals from maximizing lifespan to seeking the longest possible healthspan? What does it take find joy despite the losses and limitations of aging? How do we live fully deep into old age?