Morata was bought by Chelsea in 2017 for £58 million in what was widely regarded as a statement signing by the west London club.
Thereafter, he struggled with injury and poor form before eventually joining Atletico Madrid on loan in January.
In an interview with Goal (opens in new tab), Morata expressed his disgruntlement and overall sadness at how things unfolded in London.
"I didn't quite feel loved or appreciated by the club or the fans. I started very well at Chelsea, but an injury in the end leaves you a bit stuck," he said.
"As bad as it was, I still scored 15 goals and won the FA Cup... but I was out of the World Cup, and for me that was the hardest thing that could happen to me in my life.
"I've dreamed of being able to play in a World Cup since I was 10 years old, and I chose Chelsea because I thought it would be the best club to later be able to play in the World Cup."
Morata went on to say that Atletico Madrid – his boyhood club – saved him, and that Diego Simeone et al have turned his life around.
The 26-year-old scored six goals in 17 games after joining the Rojiblancos on loan last term, and is desperate for the clubs to make his move permanent.
"It motivated me a lot that Simeone called me, no matter the club I was at, and told me that I could be important in Atletico," said the striker. "The squad and the club staff have changed my life."
"We will see what happens in the negotiations between them, but the two clubs already know what I want. I only ask, please, as I said to Atletico, do everything possible to do it as soon as possible. Because I just want to be here."
Thank you for reading 5 articles this month* Join now for unlimited access
Enjoy your first month for just £1 / $1 / €1
*Read 5 free articles per month without a subscription
Join now for unlimited access
Try first month for just £1 / $1 / €1