By Caroline Cheese
BBC Sport at Wimbledon
Serena Williams said it was "not easy" to accept defeat to Maria Sharapova in the Wimbledon final, but vowed to recover quickly.
"I don't know what happened - I didn't play great and I didn't win," said Williams, who won in 2002 and 2003.
"Perhaps I put too much stress on myself. I wanted to win more than anything.
"I'm at 20% right now and I'm definitely going to triple my effort and do everything I can to play better."
After Sharapova clinched her first Grand Slam title, Williams went around the net to congratulate her opponent and admitted afterwards she was pleased for the Russian.
"I was really happy for her because I know that feeling and that moment and there's nothing better," she said.
"She was so excited and I always try not to be a bad loser."
Williams, who dabbled in acting and fashion design during an eight month injury lay-off, insisted her motivation to win Grand Slam titles was as strong as ever.
"I have a lot of stuff to look forward to," she said.
"Playing-wise I can just do so much better - everyone can see that."
With a smile, she added that she would be working on "my volleys, my serve, my forehand and my backhand".