As part of its ongoing series that profiles older adults who are still in the work force, NPR takes a look at fitness instructor John David, who at 73 is enjoying a second career as a fitness instructor for fellow seniors. David had been a television producer for years and in his 50s, noticed that older people at the gym don’t get as much attention from the personal trainers. So he began offering training help at retirement homes and senior centers, focusing on helping older adults get fit and enjoy their health more. For David, it is not just a job he loves, it is a calling. And it shows that not everyone works past 65 because they don’t have enough money. For some, work is its own reward.