Actor Sean Astin is tackling his toughest role: to conquer the Ironman Triathlon World Championship race in Kona this October

Sean Astin has long portrayed inspirational characters in movies, such as in "Rudy" and "The Lord of the Rings." Now, however, he's taken on the toughest role of his life, to become an Ironman triathlete capable of conquering the World Championship race at Kona this October. My story on Astin for ESPN.com's Endurance Sports section: http://espn.go.com/sports/endurance/story/_/id/13581427/endurance-sports-sean-astin-embracing-new-role-triathlete-champions-charities