Part of my Happiness Project (more on that later) was to read a self help book each month. For April I read "Authentic Happiness" by Dr. Martin Seligman. One of the main parts that stuck with me was the difference between pleasures and gratifications and how they affect our long term mood.
Pleasures are things that are felt through the senses that bring enjoyment but don't really alter your more permanent state of being. For example; hot showers, eating good food, smelling chocolate, getting a massage, watching t.v., laying in the sun. These things feel good in the moment but when they are done the emotional high is done as well.
Gratifications are things that don't always feel good in the moment but they give more long lasting emotional highs that affect mood after that activity is done. For example; reading a book, parenting, marriage, exercise, volunteer work, being with friends, cooking a meal, cleaning your house.
This idea really stuck with me because I have found that when I am feeling low it is easier to do the pleasure things but when they are over I go back to feeling down. The trick is to balance both items so there is happiness in the present and more long term.
This web page is a synopsis of the book and gives you the main idea of what the book teaches.
Also this month in the Ensign is an article about happiness that quotes Dr. Seligman.