Complete article from Real Simple here
1. Raise your activity level to pump up your energy. If you're on the phone, stand up and pace. Take the stairs instead of the elevator. Put more energy into your voice. Take a brisk 10-minute walk.
2. Take a walk outside. Research suggests that light stimulates brain chemicals that improve mood. For an extra boost, get your sunlight first thing in the morning.
3. Reach out. Send an e-mail to a friend you haven't seen in a while, or reach out to someone new. Having close bonds with other people is one of the most important keys to happiness. When you act in a friendly way, not only will others feel more friendly toward you, but you'll also strengthen your feelings of friendliness for other people.
4. Rid yourself of a nagging task. Deal with that insurance problem, purchase something you need, or make that long-postponed appointment with the dentist. Crossing an irksome chore off your to-do list will give you a rush of elation.
5. Create a more serene environment. Outer order contributes to inner peace, so spend some time organizing bills and tackling the piles in the kitchen. A large stack of little tasks can feel overwhelming, but often just a few minutes of work can make a sizable dent. Set the timer for 10 minutes and see what you can do.
6. Do a good deed. Introduce two people by e-mail, take a minute to pass along useful information, or deliver some gratifying praise.
7. Save someone's life. Sign up to be an organ donor, and remember to tell your family about your decision. Do good, feel good―it really works!
8. Act happy. Fake it 'til you feel it. Research shows that even an artificially induced smile boosts your mood. And if you're smiling, other people will perceive you as being friendlier and more approachable.
9. Learn something new. Think of a subject that you wish you knew more about and spend 15 minutes on the Internet reading about it, or go to a bookstore and buy a book about it. But be honest! Pick a topic that really interests you, not something you think you "should" or "need to" learn about.
Some people worry that wanting to be happier is a selfish goal, but in fact, research shows that happier people are more sociable, likable, healthy, and productive―and they're more inclined to help other people. By working to boost your own happiness, you're making other people happier, too.