Jon Lester announced his retirement Wednesday, ending a 16-year career with three World Series rings and 200 wins primarily with the Boston Red Sox and Chicago Cubs.
Lester, 38, started at least 30 games in 12 of those seasons and was a five-time All-Star.
Lester made 28 starts last season, where he began with the Washington Nationals before a trade sent him to the St. Louis Cardinals.
Current Cubs manager David Ross said Lester was the hardest worker he's ever been around.
But Lester told ESPN on Wednesday that he didn't want to put his body through the rigors of another season.
"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 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."
A dominant postseason competitor with an intimidating, fiery demeanor on the mound, Lester won World Series titles with the Red Sox in 2007 and 2013. He joined the Cubs as a free agent and was the ace of the staff in 2016 when Chicago won the World Series in seven games over the Cleveland Indians.
Lester signed a $155 million deal with the Cubs in what then-GM Jed Hoyer said set the stage for the team breaking a 108-year World Series drought. Hoyer said Lester signed specifically with the intent of getting the Cubs a title.
He made three appearances in the 2016 World Series and during the team's peak, 2016-2018, appeared in 10 playoff games with a 1.93 ERA.
Lester was diagnosed with cancer following his big-league debut with Boston in 2006. He underwent chemotherapy for anaplastic large T-cell lymphoma but was back with the team by midseason 2007.
--Field Level Media