Gareth Barry has admitted the fear of "going stale and falling into a comfort zone" was a major factor in him deciding to quit Aston Villa and join Manchester City in a £12m move.
And the England midfielder revealed the regret he felt in not being able to help bring trophy glory to the midlands club for whom he made 440 appearances.
But he is confident that he can achieve such goals with City after holding talks with manager Mark Hughes despite being made a "fantastic" new contract offer by Villa.
Barry, who came close to moving to Liverpool last summer, took the unusual step of explaining his reasons to leave Villa after 12 years in a letter to the Birmingham Mail.
He wrote: "After all the speculation over the last 12 months, I want the chance to explain my decision to the Aston Villa fans.
"I want to thank them for the incredible support I have received over the last 12 years and this football club has been a huge part of my life.
"I joined as a 16-year-old boy and 12 years later I am moving on as a 28-year-old man with a wife and two children. A lot of things have changed in that time - players, management and a chairman.
"But every season bar none, whether we have been bottom half, mid-table or challenging for Europe, the support myself and the team have received has been fantastic.
"My one huge regret is that during my time at this club we have not brought the fans the success they deserve and I obviously have to take my share of responsibility that we have not been good enough to win trophies.
"I feel the club is in the best position it has been in during my time here. I think we have a group of very good young players, we have a fantastic chairman who is here for the good of the club, and one of the best managers in the game."
Barry added: "Obviously people will ask why I am leaving if I feel like that. I have honestly been very undecided what to do.
"The manager and the whole club have bent over backwards to try and persuade me to stay and made me a fantastic offer which I am extremely grateful for.
"But, after changing my mind lots of times, I came to the decision that the time was right for me and for the club to part company.
"I need a new challenge, I have a massive fear of going stale and falling into a comfort zone.
"I believe the deal is a good one for the club. I am sure the manager will use the money well to strengthen the team and the club will go from strength to strength. I am also excited now about my new challenge."
Barry had spoken of his desire to play Champions League football and admitted: "A lot of people will question my decision to join Manchester City.
"They were the club prepared to meet the valuation which, for a 28-year-old with a year left on his contract I think shows how much they wanted me.
"Once I had spoke to Mark Hughes, there was nowhere else I wanted to go, I was also desperate to avoid any long drawn-out saga. I feel I am joining a club that will seriously challenge to win major honours.
"People might doubt that, but I am convinced with the plans the club has short term and long term, and the backing the manager will receive from the owners, that we will be a major force."
Barry also feels he will have the best chance of staking a claim to be part of the England team at the 2010 World Cup under the role he will be operated in by Hughes.
He said: "Also the World Cup has always been a major part of my thinking and I feel at Man City I will get the chance to play regularly in my best position and play a big part in a successful side.
"Time will tell if I am right or not, but those are my reasons."
Barry insists he will be leaving Villa on good terms this summer after all the speculation surrounding the move to Anfield 12 months ago.
He said: "I have grown bored of all the speculation surrounding me over the last 12 months and I am sure all the fans have as well. I am glad I never left last summer because I would have left under a huge cloud. This year I feel things are different.
"I haven't used an agent. I have discussed things with my best friend but ultimately made my own choices and I think the situation has been handled properly by everybody involved and once again I have to thank the manager and the club for that.
"I genuinely wish the club all the best for the future, and want to thank everyone who has helped and supported me in my time here. For the rest of my life, Aston Villa will be the first result I look for."Reuse content