The former Arsenal captain will return to the Premier League this summer after the Blues secured a transfer, reported to cost around £27m, last week.
"I asked Barcelona to find a way for me to leave the club," Fabregas told Cadena Cope. "The president tried to stop the sale, but I already had my mind made up.
"At the time, I spoke with [sporting director] Andoni Zubizarreta and the president and I told them I wanted to leave. Honestly, it all went really smoothly. I'm not leaving for any specific reason, if not for a multitude of different things, my own errors and that's it.
"If I didn't think that I'd be happy at Chelsea, I would've never made this decision. Above all, I want to be happy both professionally and personally."
Fabregas joined Barcelona in 2011 after eight years with Arsenal.