"I was a sad, miserable human," Luck said in an interview with the Indianapolis Star's Zak Keefer. "I was not nice to myself, nor was I nice to anyone else. I was a miserable SOB to be around. I was nervous. I was scared."
In January 2017, Luck underwent surgery on his shoulder in a procedure that addressed an injury he suffered back in 2015. The recovery cost him the entire 2017 season, during which Jacoby Brissett took over as the Colts quarterback.
Between his surgery and all of the pain he dealt with prior to going under the knife, Luck told Keefer he started wondering about his future in the sport.
"There was an uncertainty, an apprehension," Luck said. "I was scared, scared in my core, in my insides. There was a time I was very scared about football, and about my place in football."
Doctors finally cleared Luck for a return to the field in July.
He appeared in three of Indianapolis' four preseason games, going 20-of-32 for 204 yards, one touchdown and an interception.
When healthy, Luck is one of the NFL's best quarterbacks. He threw for 4,240 yards, 31 touchdowns and 13 interceptions in 2016—numbers that are even more impressive when considering he was battling a lingering shoulder injury.
According to OddsShark, the Colts are +550 to win the AFC South, which are the lowest odds in the division. Luck's return doesn't single-handedly make the team a playoff contender, but he offers the type of stability first-year head coach Frank Reich can build on for 2019 and beyond.