INDIANAPOLIS -- There wasn't a look of anger or dismay on Andrew Luck's face after the Indianapolis Colts' playoff loss to the Kansas City Chiefs on Saturday.

Frustration? Definitely.

The Colts played their worst game of the 2018 season at the worst possible time, ending an otherwise impressive 10-6 season.

There was really more of a look of relief on Luck's bearded face. As much as he talked in a positive mind frame about being back on the field again after missing the 2017 season, he knew deep down he had to prove the pain in his shoulder was gone for good, prove he could be durable again, prove he could overcome any fear he had about playing again and prove he could get through a full season after nearly three years of shoulder problems.

He did all those things.

That's why Luck had every reason to talk about being happy and having fun again, because he didn't miss a practice or a game for the first time since the 2014 season and was again one of the leaders on a young team that surprised many by making the playoffs after a 1-5 start. As Luck cleaned out his locker on Sunday morning, the franchise quarterback didn't have to think about lining up an itinerary of what his rehabilitation schedule would be like on his right shoulder during the offseason.

It's all looking forward, not back, for Luck and his shoulder after a 2018 season that has him considered the front-runner for the NFL's Comeback Player of the Year award.

"Just really felt he was at peace, in a zone, enjoying the moment, and ... it's because at the end of the day, he's one of those elite mountain climbers," Colts coach Frank Reich said. "I think what I respected most about him, although I know he wants to get to the top [of the mountain], for him, it's all about the climb as well.

"And [is] all about the men that he's climbing up with. I really think that oozes out of him, and I think what we tried to do this year was create a culture where that was a premium. I think he was confident and comfortable in doing that."

Just as the Colts were back this season, Luck was back and even better than he was before his rising career came to a halt in Week 3 of the 2015 season because of the shoulder injury. For as good as Luck's stats were -- second in the NFL in touchdowns (39) and a career high in completion percentage (67.3), completions (430) and attempts (639) -- his rejuvenated belief in having fun again and not letting the game consume him stood out.

His football schedule was as detailed as possible because Luck wouldn't have it any other way, but he allowed himself to enjoy time with his teammates, friends, family and girlfriend even more during the season instead of waiting until after the season to do those things.

"In past seasons there's been a mass of emotional letdown or flip in the season," Luck said. "Now I can try to be a good boyfriend. But it doesn't seem that way this year. I think one of my challenges for myself was to maybe not saddle everything in my life so much, but be able to exist as a happy human throughout the season. Not just after the season. I don't have this desire to run away and hide for a couple of weeks, if that makes sense."

The Colts were back in the playoffs for the first time since 2014. They beat AFC South foe Houston in the wild-card round before being thoroughly outplayed by the Chiefs, 31-13, in the divisional round.

Luck never found a rhythm Saturday. He had five of his passes batted down at the line of scrimmage, didn't lead the Colts to a first down until their fifth possession late in the first half, and he finished the game just 19 of 36 for 203 yards and a touchdown.

"It's been a rewarding season in many ways," Luck said. "This is not the end that anybody in that locker room wanted. We wanted to go 1-0 this week and continue on this journey. But I'm very thankful I could play football, thankful to be in a locker room, to run on the field and throw it to my friends. It was a rewarding season, a fulfilling season. I think I improved as a quarterback. And I know I have a lot more improving to do."

Luck isn't preparing to meet with doctors, physical therapists or trainers, and he plans to not throw a football "for a while." He'll tweak his game some in order to hopefully be a better quarterback for what should be a better team next season.

"He has to be fired up to have a normal offseason, to get away," Reich said. "I know he's Andrew, and he's still going to do his deal, be disciplined. But [also] relax. My encouragement to him would be you better do that, better take advantage of it and get some rest, and I'm sure he will."