"You know what, I need to push it a little more. I just need to be a little more irritable," Campbell said. "Which I can do that."
Detroit dropped to 9-4 following a dismal second half in which it racked up just 76 yards of total offense while ending the game with eight penalties to Chicago's four.
Quarterback Jared Goff also had one of his worst games of the season, throwing two interceptions and being sacked four times against heavy pressure.
"Coaching point is discipline across the board, and that's why I bring that up. We've been a disciplined team and we just weren't enough today, and they were," Campbell said. "And ultimately, we played their game. We never really got to play our game."
Bears quarterback Justin Fields also continued to thrive on the ground against the Lions' defense with 12 carries for 58 rushing yards, in addition to 223 passing yards and a passing touchdown.
Against the Lions, Fields is now averaging 90.2 rushing yards per game for his career, the most by any quarterback versus a single opponent in NFL history (minimum four games played), according to ESPN Stats & Information research.
Lions edge rusher Aidan Hutchinson was emotional after the loss, citing defensive lapses and mental errors for some of the recent struggles. Since their bye in Week 9, the Lions' defense is allowing 29.8 points per game, which ranks second to last in the league over that five-game span.
"We've just got to bounce back and we will," Hutchinson said. "We'll grow from it."
The Lions' defense has struggled to find consistency, but Hutchinson was able to end his two-game drought with a sack of Fields at 6:14 in the second quarter. It was the 16th sack of his career and the most by a Lions player in 30 career games.
However, Hutchinson was flagged for an offsides penalty that resulted in a 38-yard passing touchdown by the Bears, as Fields found DJ Moore at 1:36 in the third quarter for a 19-13 lead.
"It's just a momentary lapse in judgement. I'm disgusted with it, with that play," Hutchinson said. "That play just changed the momentum of the game and that's on me."
The message from Campbell, with four regular-season games remaining, is to clean up mistakes.
"Look, I'm not going to change who I am. Sometimes I need to apply pressure in different areas. That's fine. I can do that," Campbell said. "But, hey, this is the league, man. We're still in December. That's what this is all about, you know.
"We got a pretty resilient team here. We'll bounce back, man. It was a loss, and it stings. Nobody feels worse about it than those guys do and the coaches. ... It's a hard pill to swallow. The guys we got, it only motivates you to move on and get a win."
Like Campbell, Goff is confident the Lions can correct those issues ahead of Saturday's home game against the Denver Broncos.
Goff had just 161 passing yards and struggled against pressure by the Bears, as they held him to 2-of-10 passing (for 40 yards, 2 interceptions) on throws more than 10 yards downfield, tied for his fewest completions in such situations in a game this season.
The loss also snapped Detroit's three-game winning streak over Chicago. The Lions remain atop the NFC North standings, but they're not satisfied with their overall play of late.
"It's a little reality check, like, 'OK, look in the mirror and fix it,'" Goff said. "We've got some time here in the next four games, so it starts with Denver to get it fixed and to get geared up for our ultimate goals, and yeah, it's a good gut punch that typically does our guys well."