The Spaniard is now seen as a key part of Diego Simeone's first XI, but he struggled for form in the third season of his Atletico career.
"From the first four years at Atletico, the first two were good. It was more complicated from the third. But I think I am where I am because I went through what I did," he told AS.
"I never wanted to quit. I'm very stubborn. I like difficult challenges because you're better when you come through them.
"For me, Atletico is at the level of the best clubs in Europe and this is where I wanted to be."
Garcia scored 17 times for Atletico last season.