Contentment, not happiness

I got a blazing white hot flash of crystal clear understanding today. Having thought and thought and thought over the months about attaining happiness throughout my life I came to a startling realisation- I don't want happiness. I want contentment not happiness. Contentment is deeper and more complex than happiness (which is fickle and ephemeral). I need to have meaning and purpose to achieve contentment and so my focus should be aimed towards significance of action. I guess this is one meaning of what Aristotle called "living flourishingly" or, I think, "eudaimonia".
I think this is what is meant by some humanist ideals, thoughtfully addressing ideas of how to live with one goal being constructive, significant action (maybe other goals address ideas of personal and societal growth, ameliorating distress, encouraging the strengths of others).

Now, how do I achieve non-happiness?!

Claire and I are walking a sponsored 20 miles on Ruby's 13th birthday in four weeks. Three people have independently told me they think this is an admirable thing to do on Ruby's birthday- to think of others on a sponsored walk. The truth is, what else are we to do? Sit around and mope, feeling sorry for ourselves? Fingers crossed Claire's recently injured ankle holds out.