"This is going to sound really bad, but I've always been a big believer in playing stupid," Lester said Monday night. "I've seen it. I saw it with the Rays in 2008. They were naive to the situation. They had nothing to lose. We have nothing to lose.
"We're not supposed to win. We're supposedly still in the rebuilding stages. We make the playoffs, that's just an added bonus. I like that."
• Lester to start Friday as Cubs reset rotation
Lester can speak from experience. He's been a part of five postseason teams and won two World Series championships with the Red Sox. He fell one step short of a World Series berth in 2008, when Boston was upset by the surprisingly successful Tampa Bay club managed by Joe Maddon.
"There's the point where you really like to have a lot of experience to rely upon in those difficult moments, then there's those other times -- if you think about your own life experience -- where you just didn't know enough," Maddon said. "You just walk into a difficult moment and nail it because you didn't overthink it, either.
"I kind of like that we played stupid, because I think it's absolutely complimentary."
Lester hopes the Cubs, many of them entering the first postseason race of their careers, will maintain that attitude down the stretch -- starting with two series against some of their chief Wild Card competition.
"I can sit here until I'm blue in the face and talk to these guys about what to expect and the stretch run. I've been through it all," Lester said. "The biggest thing that these guys can learn is just going through it, whether we're there at the end or not.
"You've just got to go through it, then you build on those experiences. The next year, you come out and build on that. That's all you can do. I always talk about the things you can control; that's all you can control, you worry about that."
Adam Berry is a reporter for MLB.com. Follow him on Twitter at @adamdberry. This story was not subject to the approval of Major League Baseball or its clubs.