Friday marks International Happiness Day, a United Nations-established holiday that celebrates people's positive attitudes and efforts toward the world's well-being. Happiness is a fundamental human goal, according to the U.N. General Assembly, and among the best ways to achieve it are giving, exercising and appreciating what's around you. Don't worry if you're not in the mood -- resilience, emotion and acceptance are important too.

No matter how you're feeling on Friday, take a minute to help yourself and others. Read a few of the best famous quotes about happiness, compiled from GoodReads and BrainyQuote:

"Happiness depends upon ourselves." — Aristotle

"There's nothing like deep breaths after laughing that hard. Nothing in the world like a sore stomach for the right reasons." — Stephen Chbosky

"Happiness is a warm puppy." — Charles M. Schulz

"Success is getting what you want, happiness is wanting what you get." — W.P. Kinsella

"The best way to cheer yourself is to try to cheer someone else up." — Mark Twain

"It's been my experience that you can nearly always enjoy things if you make up your mind firmly that you will." — L.M. Montgomery

"Happiness is when what you think, what you say, and what you do are in harmony." — Mahatma Gandhi

"We all live with the objective of being happy; our lives are all different and yet the same." — Anne Frank

"We're all golden sunflowers inside." — Allen Ginsberg

"I, not events, have the power to make me happy or unhappy today. I can choose which it shall be. Yesterday is dead, tomorrow hasn't arrived yet. I have just one day, today, and I'm going to be happy in it." — Groucho Marx

"The U. S. Constitution doesn't guarantee happiness, only the pursuit of it. You have to catch up with it yourself." — Benjamin Franklin

"Happiness is not a goal; it is a byproduct." — Eleanor Roosevelt

"Happiness is a perfume you cannot pour on others without getting some on yourself." — Ralph Waldo Emerson

"The word 'happiness' would lose its meaning if it were not balanced by sadness." — Carl Jung

"Happiness is neither virtue nor pleasure nor this thing nor that, but simply growth. We are happy when we are growing." — William Butler Yeats