It's a state of mind stimulated by different things. For me music of the 80's, masarap na luto ni misis( and si misis siempre :P), my growing son, contentment in life, fulfillment of my dreams in life, hopes, etc.
Happiness is a double shot of your favorite single malt in one hand, your favorite stogie in the other, sitting lazily by the porch, watching the gleaming cars in the garage on a lazy Saturday early evening.