De Bruyne has been speaking for the first since being sold to Wolfsburg for £17m in January after Jose Mourinho criticised his training methods.
However, the Belgium midfielder says those comments have not affected him as he prepares for the World Cup.
"For myself I know what I do on the field," De Bruyne told Sky Sports News.
"Physically I'm always one of the top players in the game and run a lot of kilometres.
"The second half of the season (at Wolfsburg) I showed everybody I'm a good player.
"But it's difficult to prove yourself if nobody can watch you - that's all I can say about it.
"I'm not at the club any more and I'm doing fine at the moment."