New Middlesbrough signing Stephen McManus admits leaving Celtic was an agonising decision.
The central defender, who enjoyed a successful loan spell at Boro last season, penned a three-year deal on Teesside this week rather than choosing to see out the final year of his Hoops deal under new boss Neil Lennon.
McManus' switch to Riverside brought his long-term association with his only previous professional club to an end, and the 27-year-old says he thought long and hard before opting to move south.
"It was something I thought long and hard about over the summer with the new manager coming in as well," McManus told Boro's official website.
"I have worked with Neil for a number of years and it was a really, really tough decision.
"I had a year left on my contract at Celtic, I had been there for 12 years and coming down here really opened my eyes to different things, not just on the football side of it, but the way you can live your life as well.
"It's the hardest decision I have ever had to make in my career, leaving Celtic. I had 12 wonderful years there from a kid when I left school.
"I went full time in 1998, and it was a really, really hard thing for me to do, finally walking out of the door.
"Celtic will always be a part of me, it will always be my first love in football. But I am coming down here, it's a fresh challenge and I am really looking forward to it."
McManus, who came up through the ranks at Celtic, admits pulling on the famous green and white hooped jersey fulfilled a boyhood dream.
"If somebody had said to me as a young kid that I would have played for 10 minutes at Celtic Park, then I would have bitten their hand off to do it," he said.
"To come through the ranks and to play in the first team, to win Old Firm games, to win the league, to win trophies, to play in the Champions League, to captain the club, it was an incredible feeling to do and one that will always stay with me.
"It is something I can be proud of, and I loved every minute of being there.
"But the time was right for me to move on, for the club as well. It was the right time for the club to sell me and it was the right time for me to move on.
"I wish everybody all the very best up there because it's a wonderful place and it's a wonderful club."