The Panthers earned the number two seed in the NFC but crashed out of the post-season in their first game, as they fell to a 23-10 defeat to the San Francisco 49ers at Bank of America Stadium.
"It was hard. I was salty, and still am to a degree," Newton told the Charlotte Observer.
"There's been times when I didn't even come out of the house, didn't want to come out of the house, didn't want to watch ESPN, didn't focus on the game that they played because it wasn't important to me.
"But having that same taste in my mouth will be the driving force to my preparation in the off-season."
Newton threw for 24 touchdowns to just 13 interceptions at a quarterback rating of 88.8 in the 2013 regular season.