( CNN ) -- Three-time FIFA world player of the year Ronaldo announced his retirement from football on Monday in an emotional press conference which brought an end to his 18-year career . The 34-year-old former Brazil striker , who in 2006 became the all-time leading scorer at the World Cup , cited injury and a lack of fitness as the reasons behind his decision to end his contract with Sao Paulo-based club Corinthians . `` As you can imagine and you heard during the whole weekend , I 'm here to ( confirm that ) I 'm closing my career as a professional player , '' the former Barcelona , Inter Milan and Real Madrid star told reporters at a press conference . Ronaldo , who has struggled with his weight in recent years , also revealed that he has hypothyroidism -- an illness which affects the body 's metabolism . `` Four years ago at Milan I discovered I was suffering from a complaint called hypothyroidism , which slows down your metabolism , and to control it I would have to take some hormones that are not permitted in football because of anti-doping ( rules ) , '' he said . `` The pain made me anticipate the end of my career . My career was beautiful , was wonderful . I 've had many defeats but infinite victories . '' Has Rooney joined the ranks of football 's immortals ? Ronaldo has won the World Cup twice , in 1994 and 2002 , and his 15 goals in football 's premier tournament is a record . The two-time Copa America winner played for some of football 's most-famous clubs , and also had spells at PSV Eindhoven and AC Milan during his 13 years in Europe . `` It 's very hard to leave something that made me so happy . Mentally , I wanted to continue , but I have to acknowledge that I lost ( the fight ) to my body , '' a visibly upset Ronaldo said . Ronaldo won the now-defunct European Cup Winners ' Cup with Barca in 1997 and the 1998 UEFA Cup with Inter , scoring in the final of both competitions . `` Il Fenomeno '' -- as he was dubbed after his time with Inter -- went on to win two Spanish first division titles with Real in 2003 and 2007 . But Ronaldo has suffered criticism from Corinthians fans following the club 's recent elimination from the Copa Libertadores by Colombia 's Deportes Tolima . The supporters ' anger led to the players ' cars being vandalized and `` Ronaldo is a shameless fatty '' being painted on a wall at the club 's training ground . But the veteran forward showed no ill-feeling towards the fans , and instead praised their enthusiasm . `` I 've never seen fans with so much passion , '' said Ronaldo , who was a boyhood supporter of Rio de Janeiro club Fluminense . Ronaldo 's footballing achievements have at times been overshadowed by controversy , starting with his late withdrawal and then reinstatement before the 1998 World Cup final against France -- which Brazil lost 3-0 . He has had several high-profile relationships , and after a parental test last year showed he had fathered his fourth child to a waitress he met in 2002 , Ronaldo announced he 'd had a vasectomy . He hit the headlines for the wrong reasons in 2008 when he admitted picking up three prostitutes who turned out to be transvestites . Ronaldo accused one of them of trying to extort money from him . But despite his recent problems , he will be remembered as one of the greats of the game . Meanwhile , Roberto Carlos -- who played alongside Ronaldo for Real , Brazil and most recently Corinthians -- has also ended his stay in Sao Paulo and joined Russian team Anzhi Makhachkala . The 37-year-old , who was also a World Cup winner in 2002 , had been with Corinthians since he left Turkish side Fenerbahce in 2010 . The full-back is most famous for his 11-season stay in Madrid , where he won the European Champions League three times between 1998 and 2002 .
Ronaldo has announced his retirement from football after an 18-year career . The two-time World Cup winner said the decision was down to injury and a lack of fitness . The three-time World Player of the Year also revealed he suffers from hypothyroidism . The medication required to treat the illness is banned under football 's anti-doping rules .