In his post on Twitter, Harrison wrote, “As I sit here typing this letter, my mind is all over the place. From the time I was 4 years old, football has been the center of my life. The game has taken me places at the age of 22 most could only dream of. It has introduced me to my closest friends and helped me forge relationships that will last a lifetime. Football, and its various ups and downs, helped turn a boy into a man.