Diego Costa regrets the manner of his Chelsea exit and admits to having "special affection'' for people at the club.
Costa, 28, finally agreed a move back to Atletico Madrid earlier this week and arrived in the Spanish capital on Friday, ending weeks of exile in Brazil.
The Spain striker won two Premier League titles in his three seasons at Stamford Bridge, but his stay ended in acrimony as he refused to return to the club after being informed by text message that he was not in Antonio Conte's plans.
But Costa will not let his final few months sour his time at the club.
"I didn't want it to unfold as it did, never,'' the Spain international told journalists at Madrid airport, as reported by Marca. "I have a special affection for the people at Chelsea. I am not someone who wants to stain his image. They know there the person I am.
"I don't want to have an ungrateful attitude towards Chelsea, because I was also very happy there and played in a great team. Atletico is my home and here I am."
Costa will restart his career in familiar surroundings as he is back at the club he served with distinction between 2010 and 2014.
Although he will not be able to play until January due to Atletico's transfer embargo, Costa is raring to go at a place he calls home.
"Atletico Madrid is my home and here I am,'' he added. "I am very happy. [The negotiations] went on too long, but there was a happy ending in the end.
"After three months out, I have been doing some training... I am not in as bad shape as some people have said. And here we have [fitness coach Enrique] 'El Profe' Ortega who will get me fit. I am scared of his training sessions, not the weighing scales. Motivation is never something I lack.
"It took too long, but it has ended happily. Now I want to see my teammates and start training. You always get a bit nervous as time passes. But [Atletico CEO] Miguel Angel Gil has made a big effort. I appreciate that a lot."