Smile. A 2011 study showed that thinking about something positive that makes you smile can actually make you happier (fake smiles don't do the trick), while 2003 Clark University research found that smiling activates positive memories.
Go for a run. Physical activity boosts the brain's release of endorphins, feel-good neurotransmitters that can improve mood and well-being.
Pray. Spirituality and religious involvement is linked with greater well-being and happiness, according to a review of more than 300 studies on the connection between spirituality and health, while prayer is thought to relieve stress.
Laugh. In addition to relieving stress, laughter can boost mood and reduce symptoms of anxiety and depression.
Go for a stroll in the park. There are many health benefits to spending time in nature, including, perhaps, increased well-being. One UK study showed that subjects were significantly happier when in natural environments as compared to when they were in urban environments.
Perform an act of kindness. Do something nice for someone else today -- it could make you happier, according to University of California research.
Listen to happy music. Students who listened to "happy" music while making a concerted effort to feel happier experienced elevations in mood, according to a small study published this year in the Journal of Positive Psychology.
Walk tall. Walking with an upbeat stride might make you feel happier, according to Florida Atlantic University research. In the study, walkers who were told to take long strides with their arms swinging and heads held high reported feeling happier after a three-minute jaunt than a group that shuffled and looked downwards while walking.
Meditate. Meditation may be helpful in lowering stress levels and reducing symptoms of mild depression, and has been linked with emotional well-being and improved sleep.
Keep a gratitude journal. Be thankful for what you have! A number of studies have found a strong correlation between gratitude and well-being, starting at a young age. Teaching kids gratitude in schools has been linked to boosts in positive emotions and optimism.
Go on vacation. The mere anticipation of an upcoming trip can boost overall happiness for up to eight weeks before you take off, according to a 2010 Dutch study.
Play with a puppy. Your brain may be wired to enjoy playing with puppies. One study suggested that petting a furry friend can increase activity in the left-side of the brain, which is associated with pleasure and happiness, and pet ownership has been linked with increased well-being.
Take a nap. Sleep deprivation can up your stress levels. One experiment showed that after memorizing a list of words, sleep-deprived college students could remember 81 percent of words with a negative connotation ("cancer"), and only 41 percent of positive or neutral words ("sunshine"). What's more, researchers have linked catnaps with improved mood.
Enjoy a nice cup of tea. Noticing and appreciating life's small pleasures can literally rewire the brain for happiness by shifting the brain's negativity bias, according to psychologist Rick Hanson, author of Hardwiring Happiness. "We're surrounded by opportunities -- 10 seconds here or 20 seconds there -- to just register useful experiences and learn from them," Hanson told The Huffington Post.
Volunteer. Helping others could go a long way towards helping yourself. A recent University of Exeter study found that volunteering can boost happiness, ease depression and even help you live longer, Everyday Health reported.
Have sex. Sex might just help you relieve stress and boost well-being. A study by the Institute For The Study of Labor found that people who have sex at least four times a week tend to be happier and less depressed -- not to mention make more money. Plus, it could even keep your heart and immune system healthy!
Think of happy times. Feeling nostalgic about the past can make you feel happier and more optimistic about the future, according to a recent University of Southampton study.