Last May, British triathlete Tim Don broke the Ironman world-record at the Ironman South American Championship in Florianópolis, Brazil. Don completed the 26.2-mile run, the 2.4-mile swim and the 112-mile bike ride in 7:40:23, besting the previous mark by more than four minutes. But four months later — three days before the sport’s biggest event, the Ironman World Championship in Kona, Hawaii — he broke his neck when he was hit by a truck while training on his bike. Doctors gave him three choices for treatment: he could wear a hard collar, he could have surgery to fuse his vertebrae or he could wear a halo traction brace for three months — but only the cumbersome and uncomfortable halo, which required pins to be screwed into his skull and which his doctor had described as “like a medieval torture device,” would help him to heal quickly and return to competition. Courageously, Don decided to wear the halo. Now, six months after he was almost crippled for life, he’s running the Boston Marathon. While he does not expect to win, he is certain that the race will give him closure on the injury that nearly derailed his career.