Kyle joined the Scottish Premier League club after getting out of his City contract and has been amongst the goals for Killie recently.
Speaking to the Daily Telegraph, Kyle said: "When I was playing every week for Sunderland in the Championship a few years ago I feel the way I do now.
"Every game I'm putting myself about and I'm full of confidence. I also feel that bit more wiser, although I maybe don't have the legs I had then.
"When you have confidence as a striker then it's a major thing.
"I've been through the other side and it's horrible. When you're not scoring goals, not doing your job and getting stick from the fans, it's not great.
"However, once the fans start singing your name that's why you want to be here."