I spent a year interviewing America's oldest workers. Here are their 5 tips for staying healthy and active.

Patricia Casey (left), Marilyn Gettinger (middle), and Eileen Hartigan (right) shared their biggest pieces of advice with Business Insider.

Courtesy of Patricia Casey/Marilyn Gettinger/Eileen Hartigan

• Older Americans said that mental stimulation and purpose are keys to healthy aging.
• Most workers over 80 I spoke to value routines, social connections, and staying active.
• Researchers and workers agreed that optimism and engagement support longevity and well-being.

This year...