Venus Williams says she has finally gotten over the disappointment of losing the last three Grand Slam finals and the number one ranking to little sister Serena.
The world number two said her near-misses initially left her deflated and sick of tennis, but she was now over the pain.
"I do spend a lot of time feeling sorry for myself," Venus said. "But after I pat myself on the back, I get back up.
"Last year was a tough year for me because I was mentally and physically tired.
"I was always going the extra mile to do my best but I really didn't want to practice all the time. I always felt tired, so it was a tough position to be in."
Venus, who beat Germany's Anca Barca 6-1, 6-4 on Friday to advance to the fourth round of the Australian Open, said she took a break from tennis at the end of the year to revitalise herself.
"If I'm not enjoying my tennis then I'll definitely take a step back and re-evaluate my life and things on the court," she said.
"(But) I'm enjoying it a lot, especially when I'm winning. When things get a little tight, I tend to be a little bitter about my performance, that's natural, but when I'm on a roll it definitely feels great."
Venus, 22, has not dropped a set on her way to the fourth round, where she plays Australia's Nicole Pratt, and said she was feeling good about her chances.
"I'm feeling better with every match," she said.
"Serena probably feels confident she could raise the level of her game when the time counts, and I also have that same confidence.
"I've done it in the past and I'm looking forward to doing it this tournament."
The rivalry between the two sisters is already part of tennis folklore.
Both players have won four singles titles each in their careers and both have been world number one.
They played each other in the final of last year's French Open, Wimbledon and US Open championships and are tipped to meet in the Australian Open final.
As doubles partners, they have won all four Grand Slam titles plus the Olympics.
While much has been written about their mental strengths and weaknesses, Venus said mind games are not a part of their tactics.
"At times mentally you have to be stronger and be willing to go the extra mile. But either you're a better player or not," she said.
"The mind games don't come into play, I've never seen where they could be successful so I haven't even tried them."