Those who compete in full contact sports will have injuries from time to time. Some times these injuries can be serious. I've seen fighters bruise their shin from having a kick blocked and fall in pain and swear that it was broken. Then, I've seen fighters with compound fractures still trying to fight when everyone else is trying to stop them. Outside of skill, technique, endurance, etc. there is a special thing that it is hard to teach. It is "toughness". This is a mental attitude of never giving up and refusing to accept defeat. You have to ignore pain and fatigue. The path to becoming champion goes beyond skills and training because all of the athletes at a high level are well trained and highly skilled. Outside physical attributes comes will power. Here's a couple of clips with me competing in the 2002 Shidokan World Open. I am fighting with a torn ACL (right). I manage to win semi final and final bouts against two incredible fighters (Muay Thai World Champ Matee Jedeepitak and Japan Kickboxing Champion Ryo Sakai). I tore my left ACL years prior in a kickboxing bout against 2x World Champion Robert Harris, so I knew I could will myself to finishing these bouts. Refuse to lose and never give up.
clip 1 (kicked to the knee at 4:57)
clip 2 (get tossed several times during the karate rounds, because stability is gone. buying time to get the kickboxing rounds. knee gives out at 7:19 when I throw a left front kick, after that, no more left front kicks)