Don't take it personally.
I am responsible for my own happiness, just as everyone around me is responsible for his/her own, too.
*Credits to the comments on this article. I didn't like the article all that much but I'm glad to have picked out a few gems of advice from the comments.
P.S. And that is why I love The Hitchhiker's Guide all the more.
P.P.S. I think Rule #3 is the hardest to do.