A core component of what made Federer so great for so long: the importance he placed on rest, work-life balance, and adjustments to enhance his sustainability when it came to tennis:

• “Even when I was at my best, it was important  to me to have a rewarding life full of travel, culture, friendships, and family. These are the reasons that I never burned out.“
• Federer's fitness coach: tough consistent work was necessary, but so was rest and escape. Dedication and moderation. Fresh legs were vital, feeling fresh in the head was vital. Rest and recovery weren’t a break from training, they’re a central part of the mechanics that makes training work
• He likes to mix it up, keep himself from not getting bored. “I hadn’t been around somebody that had as much flexibility in their approach that Federer does. At Wimbledon, he’d stay in different houses. He doesn’t always need to practice in the same place, or javelin one favorite meal. Federer changed coaches even as a winner multiple times. This was a pattern throughout  his career. Federer said he felt they had fallen into a routine. This was a key element in Federer’s career longevity. Too much routine can kill the joy. Too much focus can grind you down. (Of the 128 men who played singles at the 1999 French open, he was the last one still playing on tour). RF: “I never fell out of love with the sport. Never”

Federer won 80% of the matches he played, but only 54% of the points - even the best players lose almost as much as they win 

• A former coach: "the gap between the best tennis player in the world and number 4 is massive. The 200th best player in the world is closer to number 4, than number 4 is to number 3."
• Federer, like Djokovic, believed that stagnation is regression. Maintaining the same level was actually losing ground
• Built a team around him that held him to high standards. “You’re gonna doubt yourself enough. You can’t have other people around you doubting you. You have to run away from your naysayers.” Federer literally switches his dentist because he didn’t want to hear any negativity
• Became great student of prior players. This is somebody who made it to Wimbledon semis in 1968. And this is somebody who won doubles in 1954