Roger Federer says that before he won his first Grand Slam title at Wimbledon in 2003 at the age of 21, he needed to develop his physical and mental strength.

"I was like a rough cut diamond,” Federer told The Sunday Mail. "That's how a lot of people saw me. I needed polishing. I came in at a time when Lleyton (Hewitt) was unbelievably successful at a young age. So was (Andy) Roddick, so was (Marat) Safin, so was (Juan Carlos) Ferrero. They were just a bit ahead of me. I don't want to say I was frustrated, but I didn't understand why it wasn't happening for me. I was far enough behind that I was, `OK, let's push myself a little more.’

"Day in day out, my mentality improved, always being professional. I understood more and more how important fitness was. I didn't know why I was lifting weights, when it was going to help me later in a tennis match. The physical strength and the mental strength were the last things to fall into place. The mental part of my game, that was the hardest part for me... the consistency I have been able to have for long, I am quite surprised I have managed to do it for so long. ''

Former No. 1 Federer said that in 2013, when he only managed to win one title, that he didn't play aggressively enough.

The 17-time Grand Slam champion added that the 2014 “stretch is very important for me and I really don't want to have any more setbacks. I feel very confident about my chances, not only in Brisbane and Melbourne, but also beyond that.''