Perhaps happy is too complicated and tricky a word to use without some careful explanation. When we mean happy in opposition to sad, then we're speaking of something as fleeting and changeable as any other emotion. It arises and it passes away. Many of us, myself included, try to hold on to the happy moments and push away the sad ones, a life-approach about as effective as going for a walk and trying to keep seeing the pretty flower you passed 100 yards ago and not see the ugly construction site you're walking by right now.
But in these moments of aliveness, I have discovered a broader, less transitory sense of happiness. A true acquiescence to the present moment brings with it an equanimity that can contain the fleeting effervescence of joyful experiences as well as the passing rain-squalls (and even the occasional socked-in storm-fronts) of sad ones.
It's like I am finding that in the face of whatever arises, I can say not just, "I am here," but also, "Where else would I go?"