Leaving Aston Villa Football Club is the hardest decision I've ever had to make.
“I've had some amazing times and made some great friends during my time at the club and I'll always be thankful to them for giving me the opportunity to play in the Premier League.
“As has been widely reported I initially turned down the opportunity to join Manchester City. That decision was purely down to the love I have for Aston Villa and its great supporters.
“When I was made captain of Villa it was a huge honour for me and I took the responsibility incredibly seriously. I signed my new contract last season with the view of staying at the club for the duration of the deal and never with the intention to leave a year later.
“My decision to stay initially was purely based on the emotion and feelings that I hold for the club and the people there that I would be walking away from - rather than looking at the football opportunity that had been placed in front of me.”
“I've experienced some incredible low times in my career with injuries and at one point even questioned whether I would even return to Premiership level. Despite that, I've always been 100% committed to improving my game and developing as a player and a person.
“As a kid watching the game on TV and then as a young footballer you dream about testing yourself against the best in the world, to compete for major trophies and to play in the Champions League. I've proved that I can play at the very top level with England and believe I owe it to myself to take the challenge of playing for one of the biggest clubs in the world in Manchester City.
“I have been immensely proud to captain such a great club and want to thank everyone at Aston Villa - most importantly the fans - for the amazing support they have shown me during my time there.
“I am now excited for the future with Manchester City and helping the club to succeed in the coming season and beyond."