Petr Cech made 333 appearances for Chelsea and was the number one at the club for about a decade.
However, Cech found himself down the pecking order after Thibaut Courtois became number one and decided to join Arsenal in the summer of 2015.
The 35-year-old has so far won the FA Cup and Community Shield with Arsenal, but has admitted it was tough leaving Chelsea where he won 12 major honours including the Champions League.
“It was the hardest decision I have made,” he told BBC’s Premier League Show.
“I felt so good and in good form that it would be a waste to sit on the bench.
“I considered [the fans] heavily but sometimes you need to make the right decisions. I had offers from different clubs and different leagues but I wanted to stay in the Premier League.
“The main decision was the challenge of bringing back the title. We have never won the Champions League as Arsenal Football Club. That was another part. I won everything with Chelsea, why not try do the same with Arsenal.
“That was my motivation and it still is. Every day I go to work and do my best because I believe it is achievable.”