ENGLEWOOD, Colo. (AP) — Just two years removed from the neck troubles that weakened his right arm but strengthened his resolve, Peyton Manning is off to the best start by any quarterback in NFL history.

He returns to Lucas Oil Stadium on Sunday a much better player than the one who left Indianapolis teary-eyed in 2012 after the Colts let him go in favor of Andrew Luck.

Manning has four terrific targets in Denver to go with the skill, intellect, work ethic and determination he’s always had.

With Wes Welker, Demaryius Thomas, Eric Decker and Julius Thomas sharing the catches, the unbeaten Broncos are averaging an eye-popping 42 points a game. Manning has thrown for a record 22 TDs in the first six weeks, and Knowshon Moreno is keeping defenses honest with a league-leading seven TD runs.

Manning loves dissecting defenses and poring over game film but hates digging deep into his own psyche to decipher what makes him tick. Listen closely to some of his words, though:

“I love practicing every day. ... I’m still learning. ... By no means do I have everything figured out.”

Most quarterbacks blowing out 37 candles on their birthday cake tire of the tedium of meetings, practices and workouts. They start daydreaming about life after football. Not Manning.

“Everybody enjoys playing in an NFL football game, but I still enjoy the preparation, the work ... and being effective,” Manning said.

The beauty of Peyton Manning is his beautiful mind.

“His focus is on one thing and that’s trying to figure out a way to help our team win that last game,” offensive coordinator Adam Gase said.

So, when a downpour hit Denver during the fourth quarter of the Broncos’ last preseason game, Manning grabbed a ball and started throwing on the sideline. He wasn’t warming up to go back in, but “just working on his wet-ball mechanics,” Fox explained.

The Broncos didn’t retreat to their indoor practice facility during a recent snowstorm but bundled up and went outside in preparation for more cold-weather games like the one last January when the Broncos were upset by Baltimore on a 13-degree night, their only loss in their last 18 games.

Manning is driven by that defeat, and his determination to make up for it shows in his precision passes. He’s completing a career-high 76 percent of his throws. Defenses can’t double all four of his main targets.

“Somebody’s going to be 1-on-1,” Demaryius Thomas said. “But Peyton also likes to say, ‘I don’t care if you do get doubled, you’ve got to figure some way to get open.’ And so I do. We all do. That’s the great thing about Peyton. He makes everyone around him smarter.”