The Athletic Bilbao midfielder is confident that his country can recover from their 2-0 loss to Senegal, but insists that they will treat their opponents with respect
La Roja crashed to a 2-0 defeat to Senegal in a warm-up friendly for the tournament, but the 22-year-old is still confident that his team will be ready for his team's opening match on against Japan July 26.
"The other day, Senegal overcame us physically, but now we're looking to get ourselves to be in a perfect condition in time, both physically and in technical superiority," he told the Spanish Football Federation's official website.
"In that sense, we are calm because we know that it's all a matter of time and that a long, hard season is ahead of us, and for the game against Japan, we will continue to work hard to be better than our opponents.
"Respect for the opponents is the basis of success - it's one of our main strengths. Spanish football is going through a magnificent period, but any team can beat us.
"Every day we are getting better, and you have to be in top physical condition in order be at your best technically.
"We know that there are moments of pre-season that are less beautiful than others, but just as necessary."
Looking ahead to the tournament, Herrera went on to say that he is looking forward to his chance to compete at the Olympics, and that he will do his all to return to Spain with a gold medal.
"You only get one shot at the Games. We want to enjoy, but we will go for it. Football depends on many factors that can change the course of a tournament. We are looking forward to it.
"It will be a magnificent event."
Finally, Herrera went on to defend Spain's trademark passing game, despite Vicente del Bosque's team being labelled 'boring' by many observers during Euro 2012.
"[Our style] is non-negotiable. Having the ball is the aim of the game. We, and the coaches as well, think that that the best way to defend is to have the ball, and for a midfielder like me, that's great."