They added that the Dutch, who face Slovakia in the last 16 on Monday, had similar qualities to their own team who reached the semi-finals in France in 1998 but should have gone further.
"It all has to do with focusing on your target. You can celebrate reaching a quarter or semi-final but it is all about winning the final," said Cocu, who won 101 caps.
De Boer added: "That is something I missed when we played at the 1998 World Cup. Then we seemed satisfied with reaching the final four. At Euro 2000 we had the focus but failed in the semis against Italy because I missed two penalties".
"It's my experience with tournaments like this that I want to convey to this squad," said De Boer, who has 112 caps.
"So far we have not played that well but in 1998 we had a poor start as well (0-0 against Belgium) but then we really grew into the tournament," he said.
"From my own time, I remember the 1992 Euros and 1994 World Cup as a spectator and, later on, after missing Euro 1996 through injury, I started realising what it was all about," added De Boer, who quit international football after Euro 2004.
"I talk to the players individually but also in groups such as the defence," he said, adding that he would often take a player out of a group session and speak to him separately about how he could improve thereby raising the general standard.
"We didn't cheer that it would be Slovakia instead of Italy. They played great in that match and deserved the win," said Cocu who was part of the last Dutch World Cup team to suffer a second round defeat when they lost to Portugal in 2006.
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