Joe Hart says England have learned the hard way they must be ruthless to enjoy success on the international stage.
"Playing to a decent standard sometimes isn't enough," he told a news conference.
"We've got to be really ruthless at both ends of the pitch. It's the thing that probably stood out the most in the two games that we lost in the World Cup. We could have walked off easily with two victories and we didn't."
England have one of the most inexperienced squads in the competition in terms of caps, with youngsters such as Eric Dier, Dele Alli and Marcus Rashford a cause for optimism among the country's long-suffering supporters.
But Hart claimed the influx of fresh talent does not necessarily make him more confident than before his previous major finals appearances.
"I've gone in to every tournament confident in the group of players that have been picked and felt that we've been ready," he said.
"For me to say it's much different will be difficult. But they've gone. They're [in] the past.
"This is a new one. A new set-up of players. We're fresh and ready and we're going to give it all we've got. We've got all the backing we need, it's now down to us to perform on the pitch."
However, Hart offered a reality check to those hoping some of Roy Hodgson's surprise selections, such as Manchester United teenager Rashford, can catch opponents out.
"It's impossible to be an unknown quantity at such a high level and in such a big tournament," he said.