I agree with stevenk, and extend this credit of happiness, because top tier teams are known to play better with each game on international tournaments. There's a simple reason for that: players from such teams earn their money in the bast leagues, which means the highest exhaustion. This tiredness wears off during play time, the next matches should be better.
The other thing worth the mention in this context is the extremely difference between club football & international tourneys. The time you spent with your club team is intense and lasts most of the year. Contrary to that is the little time left, that you play in your national team. It's a tough difference of gameplay and the bigger it becomes, the better your club is.
Here, it all comes down to the coach. Within the rare occasions, when a national trainer sees and practices with his players, he's not only got to form a team out of them, more important is to motivate them properly. In this case, a psychological placebo is worth more, than tactical finesse. This panacea has got to do with pride to play for your country, the love you've got for it. In short: it's all about feelings.
So when I heard about 50k of English soccer fanatics singing "God Save the Queen" in Marseille, I knew they understand that concept. Let's hope that Hodgson does, too. Otherwise, there's only Wasabi's prediction left.