"It was hard to walk away from Manchester City, that's for sure. I've been there since I was 15.
"It's a great club with great supporters, but, at the end of the day, you have to think about yourself and what can make you a better footballer.
"So that's why I decided to move on to a fresh challenge.
"I really need first-team football. The thing is if you play every week you're going to become a better player and I think the manager here will be able to make me improve as well."
Flood was sold the Cardiff City dream by Sam Hammam and Dave Jones.
"I think the manager has signed a lot of quality when he already had a lot of quality from last season," he said.
"So I don't see any reason why we can't make a top-six finish here.
"But I know it's going to be tough in the Championship this year.
"Looking at the fixtures it looks a lot like the Premiership with a lot of the sides we've got to play like Coventry, Leeds, Birmingham and West Brom.
"There's a lot of good quality teams in there, so it will be a hard division to get out of. But we're going to have a good go."