To answer the question, if I could chose three things that would cause me to remain happy, they would be the following: (1) Not to ever search for happiness or attempt to be happy. (2) Not to ever search for happiness or attempt to be happy. (3) Not to ever search for happiness or attempt to be happy.
What I am driving at is, I am what could be described as a happy person, and I did not become that way until I stopped searching for happiness and attempting to be happy.
Way back in the day when I was constantly searching for happiness and trying to be happy all of the time, I constantly attempted to find happiness by doing such things as drinking heavily and using drugs, looking for love in bars and night clubs, "praying to false idols," pursuing goals that it was both impossible and unnecessary for me achieve, and bending way over backwards in futile efforts to make everyone love me.