Diego Costa insists he was "very happy" at Chelsea but is thrilled to be coming "home" to play for Atletico Madrid.
The 28-year-old has arrived in Spain to undergo a medical after it was announced on Thursday that his former club have re-signed him from Chelsea for a fee believed to be in the region of £58m.
Costa joined Chelsea from Atletico in 2014 and they have won two titles in three seasons since, with the help of 59 goals in 120 games from the forward.
But the relationship between Costa and manager Antonio Conte appeared to deteriorate this year, and Costa ended up in exile in Brazil rather than training with the team.
Regarding his departure from the Blues, the Spain international told Marca: "It's not the way I wanted to leave, ever. I have a special affection for the people at Chelsea.
"I'm not a person who is going to smear the image. They know the person I am.
"I wanted to return (to Atletico). I'm not going to be ungrateful to Chelsea, where I was also very happy, playing in a team that was great.
"Atletico is my home and I'm here."
Having not taken part in pre-season training with Chelsea, Costa may be short of peak fitness but he said: "I'm not as bad as some say and here we have El Profe Ortega (Atletico's fitness coach Oscar Ortega) who is going to have me in shape.
"The scales don't scare me, his training sessions scare me!"
The Brazilian-born forward will not be able to play for Atletico until January due to their transfer ban, but remains thrilled about the move to the Wanda Metropolitano.
"I'm very happy. It's taken a lot of time but it has a happy ending," Costa added.
"Now, I'm waiting to see my team-mates and train. I'm looking forward to giving my best as always, and hopefully things go well.
"It always makes you a little nervous when time is passing by, but (Atletico chief executive) Miguel Angel Gil has made a great effort and I'm grateful to him, like everybody at the club.
"I'm very happy and will try to show my thanks in some way."