How we change what others think, feel, believe and do
Smile. Act as if you are happy. Be active and cheerful. Get out and do happy things.
Body posture is important too. Sit up straight rather than slouching. Adopt an open or relaxed body language position. Make your whole body say you are happy. Move happily too, with a spring in your step and with relaxed swinging of your arms.
Verbally align also. Speak like you are happy, using more positive words like 'love' and 'great'. Refer to yourself less and others more. Vary the pitch of your voice, especially avoiding a monotone. Speak clearly and slightly faster (but still slow enough so people understand).
Be pleasant to others. Nod in agreement. Laugh at their jokes and ensure they can be happy around you. Avoid destructive criticism, of them, of others and of yourself.
Even by yourself, try forcing a smile. Look in the mirror and make your face look happier. Research shows that you should hold this expression for at least 15 to 30 seconds for it to be effective.
People who act happy, even when they are not, may not be ecstatic but they do end up happier than if they had just wallowed in their own misery. The Facial Feedback Hypothesis says that if you just smile, forcing your lips, you will soon feel happier (Strack et al. 1988). Research has shown that just clenching a pen lightly between the teeth (hence creating a 'smile') will soon make people feel happier.
When we do something that is contrary to our beliefs about ourselves, then we feel the tension of conflict between our beliefs and actions. As a result we will move to resolve this tension by changing one or the other. When we force ourselves to smile (and keep smiling), then the only option is to change what we believe, and believing we are happy will lead us to actually feel happier.
There is also a reciprocal social effect: when you are happy with others, they will more likely be happy with you, thus setting up a social mood of happiness that will help you all.
It is worth noting that just forcing back your lips will not immediately make you ecstatic. This is an incremental effect and which needs a little time to work. 'Happier' is a relative term and if you have a deep unhappiness it will not necessarily go away of its own accord. Nevertheless, just smiling can provide temporary relief and help you cope with where you are now.
McIntosh, D. N. (1996). Facial feedback hypotheses: Evidence, implications, and directions. Motivation and Emotion, 20(2), 121-14