I too am an American, I was born and raised in this country and have much to thank it for.
But, I do agree with Greek Goddess that it's a bit sad that something like 9/11 has to occur in order for peoeple to realize their sense of pride in their country.
You wanna prove you're 'proud to be an American'? Back it up with something that isn't just words. Help out in a local homeless shelter, pick up the trash you see by the side of the road, and for god's sake..VOTE!