England started their bid to reach Euro 2016 by beating Switzerland 2-0 on Monday night, and Hart insists that the mood in the squad has always been good, despite their disappointing World Cup campaign.
"It is a new campaign so three points was vital against one of the main contenders for the group," the Manchester City goalkeeper told reporters. "It was a really good result.
"We've always been confident. I can't remember a performance when we didn't play with confidence. We played well, executed a plan and we got the victory.
"We are fighting for the European Championship. We've learnt from the summer, taken the positives and negatives, and we're going to take them into this campaign and hopefully get to France as soon as possible."
England return to action against San Marino on October 9.