Johnson, right, has suffered from depression and stress since retiring seven years ago after a brilliant career Boston Globe via Getty ImagesTed Johnson pointed to his forehead. “This was my weapon, right here,” he said. “I used the butt of my head to tackle, to get off blocks and to hit guys. It was a technique I learnt called ‘stun and separate’. I want to stun you by hitting you under your chin.”Johnson was a linebacker, one of the most brutal positions in American football.