Three-time World Series champion pitcher Jon Lester announced his retirement Wednesday after 16 Major League Baseball seasons.
"It's kind of run its course," Lester told ESPN. "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."
The 38-year-old made 30 or more starts during 12 of his 16 MLB seasons, which were most notably spent as an ace for the Boston Red Sox and Chicago Cubs.
The left-hander won 200 games, made five All-Star appearances, and posted a 2.51 ERA in six postseasons (2008, 2009, 2014, 2015, 2017, and 2018), which led the Red Sox's to two World Series championships (2007 and 2013) and the Cubs to a 2016 World Series championship, their first in 108 years.
"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]."
Lester spent his final season splitting time between the Washington Nationals and St. Louis Cardinals, posting a 3-5 record and 4.71 ERA in 28 starts.