The 28-year-old has enjoyed a positive start to his Manchester City career, scoring four goals in nine appearances since joining the Premier League outfit.
"I was focused on starting the new season somewhere else, in my case facing a new challenge with City, and after an era at Sevilla I felt it was time to finish there," he told EFE.
"You look at what you've done wrong and to continuing to work is the only thing you can do.
"There's nothing else but trying to do things right, improve every day, and remain physically and mentally strong."
Negredo scored 85 times in 180 games during his four years with Sevilla.