The Cubs had runners at first and second with one out when Herrera, who entered defensively in the ninth, connected on a changeup from Burke Badenhop.
"I was telling myself to stay back a little more and try to hit the ball somewhere where nobody can catch it," said Herrera, now 4-for-7 with runners in scoring position this season.
"You need to prepare yourself for the situation," Herrera said. "I'm here to be in those situations. I'm ready for those situations."
The Cubs had signed Herrera to a Minor League contract in December, about a month after Maddon was hired as the Cubs' manager.
"The thing I really appreciated about him in Spring Training, because I actually focused on this, was that even when he wasn't playing or was on the bench, he was always upbeat," Maddon said. "He didn't know his status, didn't ask about his status, but kept coming out and doing his job.
"I didn't know him that well," Maddon said. "I thought, 'This guy is a true professional.' He has totally exhibited that. He's got the ability to play a variety of positions. He's a pro, man. When he's one of the guys on the bench, you feel good about it because you know when you ask him to go out there, he'll be ready."
The Cubs didn't have any position players left on the bench when the 11th inning ended. Maddon had to call upon pitcher Travis Wood to pinch-hit, and he delivered a run-scoring groundout. So far, it's been a 25-man effort.
"When the [11th] inning began, I said, 'Let's get Johnny up there,'" Maddon said. "Johnny came through. Here's Johnny."
Herrera, who played for the Rockies from 2008-13 and was in 42 games with the Red Sox last year, will do whatever Maddon asks.
"It makes you feel so comfortable when you have a manager who gives opportunities to everybody on the bench," Herrera said. "He uses everybody. We appreciate that and feel really good about that."