Three-time World Series champion and 200-game winner Jon Lester is retiring after a 16-year career.

Lester, 38, told ESPN that his body just isn't up for the rigors of a major league season anymore. He made 30 or more starts 12 times during his career and 28 during his final season split between the Washington Nationals and St. Louis Cardinals.

His résumé includes five All-Star appearances and a 2.51 postseason ERA.

"It's kind of run its course," Lester said. "It's getting harder for me physically. The little things that come up throughout the year turned into bigger things that hinder your performance.

"I'd like to think I'm a halfway decent self-evaluator. I don't want someone else telling me I can't do this anymore. I want to be able to hand my jersey over and say, 'Thank you, it's been fun.' That's probably the biggest deciding factor."

Lester leaves a legacy of postseason success. He won two World Series titles with the Boston Red Sox in 2007 and 2013 and a third ring with the Chicago Cubs in 2016, helping break a 108-year title drought. Additional playoff appearances in 2008, 2009, 2014, 2015, 2017 and 2018 made him an October fixture.

Those memories will shine brightest for Lester.

"I remember the nervous feeling I had before Game 4 of the World Series in 2007," he said. "I remember standing on the mound in Game 5 against St. Louis in 2013, in a tie series, and an [paper] airplane got thrown from the upper deck that lands right behind the mound. I still remember looking at that.

"And then the turmoil of Game 7 in 2016 [when the Cubs won in extra innings]."

In his prime, the 6-foot-4 Lester dominated with a nasty cutter and intimidating presence on the mound, which included his patented look: glove resting just under his chin as he stared in for signs from the catcher.

"The cutter is what neutralized me," said Mark Teixeira, who along with Evan Longoria has the distinction of striking out more times than anyone else (22) against Lester. "He would go outside and see me diving over the plate, then he would come in with the cutter."

"The reason that he was such a bulldog was he didn't give in. And he wasn't afraid to walk guys. He knew how to pitch the lineup."

Lester is one of only nine modern left-handers with 200 wins, a .600 winning percentage and a career ERA under 4.00. Six of the other eight are in the Hall of Fame, while one, CC Sabathia, isn't eligible yet.

Off the field, Lester was known as the teammate who united the clubhouse.

"If you're building a baseball player, as far as how they treat other people, what their goals are, how you want them to compete and act on and off the field, he's the model," said Cubs manager David Ross, who was Lester's personal catcher during the pitcher's first two years in Chicago.

Lester signed a $155 million free-agent contract with the Cubs in 2015. The decision to sign with a last-place team wasn't easy.

"Him taking a chance on us when he did set the stage for everything that came," then-general manager Jed Hoyer said. "He was clearly only coming here for one reason, and everyone knew it."

Lester called signing with the Cubs "the single biggest decision we've ever made in my pro career," though he struggled in his early weeks in Chicago, with a 6.23 ERA in April 2015.

"Coming in, you're expected to be the guy to bring the World Series," he said. "I felt that early on in 2015. I was trying to win the World Series in the first month of the season. Rossy [David Ross] pulled me aside and basically told me to be myself. 'You don't need to do anything more than what you've done. Just relax and pitch.'"

The next month, his ERA dropped to 1.76, and Lester's career in Chicago took off. One online poll of Chicago fans named him the greatest free-agent signing in the city's history -- not least because Lester served as a recruitment tool to bring other stars to the Cubs.

"The reason I went there is I knew they had a chance to win a championship because Jon Lester went there," said former big leaguer John Lackey, who signed with Chicago in 2016. "He changed that organization, but that was a signal to the baseball world they were serious. That put them on the map for veteran guys."

In his second year in Chicago, Lester went 19-5 with a 2.44 ERA and was named National League Championship Series co-MVP. He pitched three times in the World Series against Cleveland, including a relief appearance in Game 7, on his way to a third World Series ring.

"I don't want someone else telling me I can't do this anymore. I want to be able to hand my jersey over and say, 'Thank you, it's been fun.' That's probably the biggest deciding factor."

Jon Lester, on his decision to retire

It was the start of a remarkable postseason stretch. From 2016 to 2018, Lester compiled a 1.93 ERA in 10 playoff appearances.

"He worked harder than anyone I've ever been around," Ross said. "When it was time to work, he was going to work. When it was time to play, he was going to make sure everyone had a good time. That's probably the biggest compliment I could give him."

Lester began his career with the Red Sox in 2002 and made his big league debut in June 2006.

Late that season, back pain sent Lester to the hospital, where he was eventually diagnosed with anaplastic large T-cell lymphoma. He underwent chemotherapy but was able to return to the team midway through 2007.

"I was in Triple-A on a rehab assignment in Pawtucket after cancer," Lester said. "My parents were there and they were leaving that day or the next day to go home, and I told them they have to change their flight and I said, 'I'm starting the next night in Cleveland.'

"That's one of the top moments of my career. Seeing their faces was pretty cool. Once I got back to baseball, I tried not to take anything for granted and really appreciated being around the guys."

The experience led to the creation of Lester's charity, NVRQT, short for 'Never Quit,' which helps fundraise for pediatric cancer research. He will continue with the foundation in retirement.

Lester's time in Boston left an impression on him.

"It makes you grow up really fast, and it's an awesome, awesome place to me," Lester said. "It made me more accountable than if I was somewhere else."

Lester threw 5⅔ shutout innings against the Colorado Rockies in Game 4 to clinch the 2007 World Series title. In the 2013 World Series, Lester went 2-0 with a 0.59 ERA against St. Louis.

"Any time he had the ball, it was a different feeling as a teammate," former teammate Dustin Pedroia said. "The power, the way he worked, the will to win. He had great stuff, but his best gift was he found a way to win. That's something you can't teach, you can't coach. It's a special player that has that. There's not many."

Lester was traded to Oakland in 2014 and started a wild-card playoff game, which the A's eventually lost, before signing with the Cubs that offseason.

After the 2020 season in Chicago, Lester signed with the Nationals. Dealt to the Cardinals at the trade deadline, he went 4-1 with St. Louis while winning his 200th and final game in late September.

"Playing with Waino [Adam Wainwright] and Yadi [Yadier Molina] was awesome," Lester said. "It was a cool experience to play for that organization. You learn to understand why they're so successful every year."

The Cardinals earned a wild-card berth, allowing Lester one final postseason opportunity. But by the end of the season, particularly after a COVID-19 quarantine in 2020, Lester knew it was time to go.

"The part that helped me be OK with this was quarantine," Lester said. "I was home, at a time of the year I wasn't normally home. That opened my eyes. ... When the work outweighs the joy, then it's kind of time to reevaluate where you're at."

Lester said he might consider television work and didn't rule out coming to Cubs spring training to tutor young pitchers -- but full-time coaching isn't in the cards. He said he will miss many aspects of the game but knows he lived up to one commitment he made to himself.

"I never wanted fans to leave a game and ask, 'Was the effort there?'" Lester said. "I think I always gave it."