"They are players who have won a great deal, almost everything, and they see things through different eyes compared with five or six years ago," Del Bosque told AS.
"That is the only fear I have. It is fundamental to be humble, sporting and good lads, nice guys. We have to forget about the past and not revel in what we won in the years before.
"We are going to another World Cup, a different one, in a different country and on a different continent, and we have to go there with the same spirit as in South Africa.
"That's the most important thing."
Del Bosque reiterated his desire for his team to show "humility", and acknowledged his side will be favourites to defend their crown.
Spain – who will face 2010 finalists Netherlands, Chile and Australia in Group B – will face stiff competition from several nations in Brazil, something Del Bosque is well aware of.
"Humility is not an empty word," he said.
"When I ask for it, it is because I know it is the path to success. Spain has a good national team and is not inferior to anyone but we must be cautious.
"We are the team to beat and there are powerful opponents, mainly the South Americans including Brazil, Colombia, Argentina and Chile.
"Then there are the Europeans, teams like Germany, Holland or Portugal. It is not easy and we have to show respect for all our opponents."