Rafael Nadal, 40, says constant self-doubt and competing against the best players in tennis made him a better athlete.

On Monday’s episode of Bloomberg’s “Leaders with Francine Lacqua” podcast, the tennis legend talked about the mindset that kept him throughout his tennis career.

“I always had doubts and, for me, doubts are good,” Nadal told podcast host Francine Lacqua. “For me, doubts are positive because they allow me to go out on the field knowing that I need to improve.”

Nadal said he didn’t let success make him complacent. Instead, he believed there was always more work to do.

He added that his doubts were not about whether he was good enough, but whether he was doing enough to reach his potential.

“It’s easy to say, okay, I’m winning. I’m super good. I keep practicing. But you lose that feeling of going to the court every day with the motivation and determination to improve something,” Nadal said.

He added that going to the court to practice or stay in shape was never enough to inspire him.

“My motivation was always to go out on the field with the determination to improve something,” he added.

Beyond doubt, his “healthy” rivalry with Roger Federer and Novak Djokovic also made him a better player, Nadal said.

“We push each other to the limit,” he said. “Our rivalries help us improve our level of tennis, our mentality, pushing our possibilities to the limit because we knew that if we did not do things more or less perfect almost every day, the other will be better than us.”

Still, they all have “enormous respect” for each other, Nadal said.

“At the end of the day, we are achieving our dreams. So why do we have to fight in a negative way?” Nadal said.

Nadal retired in 2024 after one of the most decorated careers in tennis history that included 22 Grand Slam singles titles. Former world No. 1 for 209 weeks, he is widely considered the greatest clay-court player of all time, having won a record 14 French Open titles.

Nadal joins a growing list of athletes who have opened up about what helps them stay at the top of their sport.

Masters Champion Rory McIlroy He has said that imagining the worst-case scenario helps him stay mentally alert during competition.

“If you’re trying to overcome performance anxiety or nerves, I try to think, well, what’s the worst that could happen? I’m not going to die on the golf course,” McIlroy said in a 2025 interview.

NBA legend Michael Jordan has said his relentless competitive mentality is what drives his success both on and off the court.

“I’m cursed. That’s just who I am. And I try to use it in the best positive way I can,” he said in an interview in April.