Luka Modric is probably the greatest Croatian football player in history. He has led the national team to big victories and great results, and he has played with Real Madrid for ages and won all sorts of trophies with the club. It might seem easy to think that life has been easy for him and that it has always been obvious that he would become a success, but that isn't necessarily true.
Source: Bing Designer
If you read the quote, you can see that he decided to believe in himself and that he had the capabilities to become a pro footballer, even when the surroundings told him otherwise. When he didn't get playing time, when he fought hard at the training field, when he missed a penalty, and even so.
Do you trust yourself that you have the capabilities needed to improve and to become better, or are you listening to your surroundings as they tell you otherwise?