Another one of those concepts that you have to trip over your tongue a few times before you get it.
When some body gave me some thing, or said some thing nice, or I saw some thing cool, it made me happy. It seemed to be a fleeting emotion. It never stuck around very long.
I struggled with it well into the program of AA. Imagine my shock when I finally discovered that happiness was my own responsibility, or choice. Today I still have to stop some times and remember that it is my job. I do it by reflecting on (you guessed it) my gratitude list. (wich grows each time I reflect on it) The first thing on that list is that I now have the ability to remember.