Joachim Low's side will be looking to go one better than their semi-final exit in South Africa four years ago, when they kick-off their campaign in Brazil.
And Borussia Dortmund defender Hummels believes that his compatriots need to show their fighting spirit if Germany want to reach the final.
"For me as a central defender it is crucial that [your play] is filled with the necessary aggression and passion, this is the key to success – whether at a World Cup or in the Bundesliga,” Hummels told Kicker.
“It is only when reputable defences work really well, and not because you have to, but because you want it.”
Hummels is likely to partner Arsenal defender Per Mertesacker in the centre of Germany’s back four and the 25-year-old believes he has successfully adjusted to their partnership after some rocky early showings.
"In the first few games with Per, I did not manage to change my game accordingly because I remember the 5-3 loss against Switzerland before the European Championship in 2012 as well as the game against Paraguay,” Hummels said.
"Now I know that I must do some things differently than usual and, because I know that, I can do it."
Low’s side kick off their World Cup campaign against Portugal in Salvador on June 16.