Everyone gets older, but not everyone bows out of competition in middle-age. Journalist Jeff Bercovici wanted to know: Why? Why do some athletes flame out in their 30s and 40s, while others are still going as senior citizens? Is it genetics? Special training? Diet? And could amateur athletes achieve similar results? Outside editor Chris Keyes talks with Jeff about his new book, Play On: The New Science of Elite Performance at Any Age, and what it takes to reverse the effects of getting older.