One way to increase positive emotions (happiness) is to be grateful on a daily basis. Research studies have prompted people to be grateful by writing down three things for which they are grateful every day. Those who did so increased their level of well-being in just one week! These are directions given by these researchers for doing this exercise. Try it and see if you any improvement in your mood.

Each evening, write down three good things that happened and why you think they happened.

Caveat:  Be careful in thinking that you should be grateful for everything in life (e.g. that your partner becomes violent every once in a while).  That is not the point of this exercise.  There are things in life that are negative and seeing them as positive may not be smart.  Negative emotions are as functional as positive emotions; the key is to have more positive than negative.  Hence, find things for which you are grateful in a way that it overpowers those things for which you are not grateful.

Seligman, M. E. P., Rashid, T., & Parks, A. C. (2006). Positive Psychotherapy. American Psychologist, 61, 8, 774-788.