I never really know why I feel happy after watching (500) Days of Summer. As it isn't exactly the happiest of stories. I think its because you watch Tom go through emotional pain and then pick himself up and carry on with his life, making it better, which gives you this kind of can do feeling. Like your made of stronger stuff. Because everyone has been through feelings like he experiences, and if you haven't... The possibility is that you are the one causing it or you're just a very lucky and upbeat person. Who knows! Cheerful thought to end a post with. Thumbs up!