In sports, you simply aren't considered a real champion until you have defended your title successfully. Winning it once can be a fluke; winning it twice proves you are the best.
“This year I guess I decided in the bigger matches to take it more to my opponent instead of waiting a bit more for the mistakes. Yeah, this is I guess how you want to win Wimbledon, is by going after your shots, believing you can do it, and that's what I was able to do today.”