The Bears are disappointed not only about losing their season opener to the rival Packers Sunday night in Green Bay but how they lost, failing to protect a 20-0 third-quarter lead.

But coach Matt Nagy has vowed that his team will not sulk or pout—not with players and coaches having to learn from their mistakes and prepare for next Monday night's home opener against the Seahawks.

"We need to make sure that we stay positive," Nagy said Monday. "I'm not by any means saying that anybody shouldn't be feeling the way they feel. Trust me, we all feel that way. [But] we can't sit and live in the past. We're not going to be pessimistic. We care about it. It matters to us. But we're not going to be glass-half-empty people. We will not. We won't do that."

The Bears dominated the first half, at least doubling the Packers in first downs (8-4) and total yards (160-71) while building a 17-0 lead. Mitchell Trubisky led the offense to a touchdown and field goal on its first two possession and new outside linebacker Khalil Mack powered the defense by generating two takeaways, including an interception that he returned 27 yards for a touchdown.

But after the Bears increased their lead to 20-0 early in the third quarter, the Packers completely reversed the game's momentum. Returning from a knee injury that had sidelined him for two series, Aaron Rodgers engineered four straight scoring drives to rally the Packers to their fifth straight win over the Bears. The two-time NFL MVP threw three touchdown passes in the fourth quarter to turn a 20-3 deficit into a 24-23 victory.

"It was one that hurt, just like I said last night," Nagy said. "It's one that, once our guys get in here and see the tape, they'll realize that it was really a tale of two halves, stating the obvious, and that's on both sides of the football, offensively and defensively.

"We've got to really have that finish mentality. We can't talk about it. We've got to do it, everybody included. Our guys need to understand that close isn't good enough, which they will. They know that, and they understand that it's a long season. Nobody wanted this game more than we did. It definitely hurts, like I said last night. It stings.

"But we need to use this. We need to go and use this to get better. If you have the negative, pessimistic approach to it, then that's all wrong. We're not going to have that. We're not going to have it as coaches, we're not going to have it as players. We're going to learn from it, and it's my job as a head coach to make sure they learn from it. Trust me, I'll be harder on myself more than anybody. I've done that. I've looked at the film, all three phases, and I have a much clearer picture now today than I did last night."