I will chime in to add what I think are two key words in the pursuit of happiness; they are 'balance' and 'flow'. A sense of personal balance is, to me, the key to triggering the 'flow' which I equate to 'happiness'.
Maintaining personal balance is a constant working/mindful state. There is, to me, no such thing as a negative emotion as all emotions are an
indicator of balance.
If, to example, I find myself, silently or otherwise, raging-out at my mate for 'drinking out of the milk carton' (metaphor) and ask myself why, I
am ultimately left with myself and my boudaries which I do not feel are being respected. Then I ask myself if those boundaries are legitimate, or are
they a measure of control.
At this point the anger disapates because I am now on a journey of introspection which leads, by dint of being mindful of all of this and questioning
myself, to a state of... balance.
And for me, balance creates flow.
If I've got my 'flow on' it does not matter what is happening in my external environment. I can, not only deal, but can more easily see
opportunities to experience each moment in a 'positive' light. It becomes postive because I know I am examing, and appreciating, my emotions be
they 'negative' or 'positive'.
Hence, balance creates flow and I am empowered... which is, to my mind, the key to happiness.