Saucony, an athletic footwear and apparel brand headquartered in Lexington, said that former Boston College football star Mark Herzlich will act as a spokesperson for the brand and support its marketing message, “Find Your Strong.” Herzlich, who survived a rare bone cancer, is now a linebacker for the New York Giants pro football team. The “Find Your Strong” campaign seeks to inspire and engage consumers to “find their personal ‘strong’ through running.”