As he prepares for tonight's World Cup qualifier against San Marino, he insists he can take nothing for granted.
He told Sport magazine: "I wanted to make sure I was in and around the senior squad by the time I was 21. So for it to happen when I was 18, you know, I was happy with that.
"But the thing with England is you can drop out of it just like that. If you switch off, or your performances with your club don't merit a squad place, then I don't think you deserve to be in it.
"If I take my foot off the pedal, I know I might not be back in that squad by the time I am 21."