The Central American nation takes on their more-fancied Dutch opponents in Salvador on Saturday, having defied the odds to reach the last eight after topping Group D before a round of 16 shootout triumph over Greece.
Navas was the star of the shootout, saving Theofanis Gekas' well-struck attempt, as the Levante man continued a stellar personal campaign.
And the custodian, who has played all 390 minutes for Costa Rica in Brazil, said he and his team-mates were not tired after their surprisingly lengthy campaign.
"We're fine. In a competition like this is logical that the player wears slowly, but there are days of rest, massage and other things to recover and reach the next opponent 100 per cent," Navas said.
"I think this will be one of the most beautiful games of our lives, we want to win and although we know we are facing one of the world powers, we have shown how we have to play. We know that anything can happen, but the team is there to win."
Navas conceded Louis van Gaal's men were favourites to progress to the semi-finals, but said he believed anything could happen.
"I think Holland is the favourite for the next match, because they have done many more things than Costa Rica across the world, but in the game can go either way, we are calm and we will enjoy it," Navas said.
Defender Giancarlo Gonzalez has also played every minute of the campaign for coach Jorge Luis Pinto, and said the quality of their opposition will not see them back down from a fight - as they have already shown after qualifying out of a group including Italy, Uruguay and England.
"Today we focus on recovery work to get fully game against the Netherlands and to continue to show what Costa Ricans are made of," Gonzalez said.
"While we have faced big-name players, we do not give us less, we have shown that compared to these figures we can to go out and get results as a group."
