Iniesta was at the heart of la Roja's success in the tournament, scoring the decisive extra-time goal in the final against Netherlands to seal a first-ever global title for Vicente del Bosque's side.
While he claims the sensation of scoring the winner was almost indescribable, Iniesta confesses he had "felt fragile" prior to the tournament after a handful of injury problems and some off-the-field issues.
"I had a slight depression, but everyone goes through that at some time in their life, don't they?" he told So Foot magazine. "I had a few personal problems which accumulated, and I also had quite a few physical problems... I felt fragile.
"[The feeling of scoring] was a coming together of all the positive words in the dictionary. Before hitting the ball I had to wait for it to drop. If I hadn't waited, I wouldn't have scored. I let gravity do its work and I scored. That was Newton!"
The 29-year-old also revealed he almost considered quitting the Barcelona academy after struggling when he first left his hometown for La Masia.
"It was the toughest experience [of my life]," he said. "It took me months to acclimatize. When I went to my room at night, I cried profusely. I was not sure of anything that summer. But if I had not returned to Barcelona, I would certainly have lived with regret now."
Iniesta went on to add that he looked to Zinedine Zidane as an example when he was a youngster, but claims his real idol was former Denmark star Micahel Laudrup.
"When I was little, I focused a lot on Zidane because he was beautiful to watch," he added. "But my idol was Laudrup.
"When you watched him play football, you weren't aware of time. It didn't matter to me whether he scored goals or not; watching his movements was a spectacle in itself."