"It may sound cliché and overused, but learn to be grateful for what you have,
rather than what you don't. If all you ever think about is how you can't afford
the things you want, how you're not "popular", how you're not "attractive"
enough or no good at anything, your life will become less and less enjoyable
before your eyes and all at your own doing. Changing the way you think about
things and the view you take on your life can have a big impact on you as a
person. Looking around you, carefully realize how lucky you are to have the
things you do, whether it be a loving family, great friends, an amazing job or
simply a roof over your head. Remind yourself of why you are fortunate to be
living the life you do, and focus on making the most of the gifts you have been
given."
http://www.wikihow.com/Be-Happy