The midfielder, now on the verge of a full England cap, is playing some of the best football of his career at Blackburn Rovers.
"Leaving Liverpool was the hardest decision of my life because they are top of the tree and any move away is a step down," he said.
"But I had to earn some respect as a footballer and that wouldn’t have happened if I had stayed. I was getting enough games there and manager Gerard Houllier was happy to let me go. But that move has been the making of me.
"Everything was easy for me at Liverpool. I was too immature and I needed to concentrate more on my football."