Mixed martial arts fighter Conor McGregor announced his retirement from the sport on social media Sunday. The former two-division UFC World Champion said he was done fighting in a statement posted to his verified Twitter early Sunday morning. Whatever you desire it's yours"This isn't the first time the mixed martial arts star has announced his retirement on social media. 'It's in my blood to fight'The fighter, a former trainee plumber, is considered one of the best in the UFC. McGregor leaves the sport ranked 8th on the Ultimate Fighting Championship (UFC) pound-for-pound list.