Patrick Venzke only recently turned 40, but even though his face looks youthful, his body is ravaged. He suffers terrible backaches, his left shoulder is wrecked and he also has knee trouble. “It’s the price I paid to pursue my dream,” he says as he drags himself up the steps of a café in Essen, Germany. Venzke became the first German national to make a National Football League roster when he signed with the Jacksonville Jaguars in April 2001—although he was never fielded in any of the team’s games. […] After a year in Jacksonville, Venzke moved to NFL Europe,...