The NFC North side won six of their first nine games during the 2013 regular season, but took just one win in their final seven.
The running back told NFL Network: "I think the culture is going to be the biggest thing that we're gonna need to improve on in our locker room. I don't know if it's gonna be anything really too difficult because we have all the pieces to the puzzle.
"We have a really good team, so it's just gonna be about just changing that atmosphere, that culture, getting us to the championship mentality in the way we prepare."
Bush joined the Lions during the off-season last year.