"One important key to success is self-confidence. An important key to self-confidence is preparation." Arthur Ashe (won 3 grand slams, putting him among best ever from the United States, inducted into International Tennis Hall of Fame in 1985, his self-confidence helped him overcome many obstacles during his career as he was the first African-American player ever selected to the United States Davis Cup team and the only black man to ever win the singles title at Wimbledon, the US Open, and the Australian Open).
"I fear no one, but respect everyone." Roger Federer (held number one position in the ATP rankings for 237 consecutive weeks and 285 weeks overall, has won more Grand Slam singles titles than anyone else, he is the only male player in tennis history to have reached the title match of each Grand Slam tournament at least 5 times, considered by many to be the greatest player of all time).
"Losing is not my enemy. Fear of losing is my enemy." Rafael Nadal (former #1 in the world, "The King of Clay", and has prompted many experts to regard him as the greatest clay court player of all time, as of the beginning of 2012, Nadal has won ten Grand Slam singles titles, He is the second male player to complete the Career Golden Slam (winner of the four grand slams and the Olympic Gold medal).
"I'm not afraid of anyone, but sometimes I'm afraid of myself. The mental part is very important." Justine Henin (former #1 in the world, Henin won 43 WTA singles titles and seven Grand Slam singles titles. Tennis experts cite her mental toughness, the completeness and variety of her game, her footspeed and footwork, and her one-handed backhand as the principal reasons for her success).
"Control the things you can control – let the rest go." Sam Stosur (She won the 2011 US Open singles title and was a finalist at the 2010 French Open. She is a former world No. 1 on the WTA Tour in doubles with Lisa Raymond from the United States).
"I never look back, I look forward." Steffi Graf (In total, Graf won 22 Grand Slam singles titles, was the first and only tennis player (male or female) to achieve the Calendar Year Golden Slam by winning all four Grand Slam singles titles and the Olympic gold medal in the same calendar year, was ranked World No. 1 by the Women's Tennis Association (WTA) for a record 377 total weeks—the longest period for which any player, male or female, has held the number one ranking since the WTA and ATP began issuing rankings).
"Tennis is 90% mental" - Jimmy Connors - is an American and former World No. 1 tennis player. Connors held the top ranking for 160 consecutive weeks from July 29, 1974 to August 22, 1977 (record at that time) and an additional eight times during his career (a total of 268 weeks). He won eight Grand Slam singles titles and two Grand Slam doubles titles with Ilie Nastase.
"Ninety percent of my game is mental. It's my concentration that has gotten me this far." – Chris Evert (She is a former world number 1 professional tennis player from the United States. She won 18 Grand Slam singles championships, Evert's career win–loss record in singles matches of 1,309–146 (89.96%) is the best of any professional player man or woman in the Open Era. On Clay courts her career match win loss rate of 94.05% (316/20) remains a WTA record).