Happiness. What a word. Over analysed and pursued from everyone.
And if someone tries to define it, then, there is usually a pause. "Hmmmm...happiness. Well...yes..." and then more pauses and then maybe a witty definition (usually after having endlessly googled the word) comes up.
I don't think I could define happiness using a simple phrase. You are happy when you are satisfied, complete, when you accomplish your goals, when you are in love, when you are free, healthy or just because you bought a nice dress that really makes your bum look fit or because you ate an amazing chocolate cake or because you got vouchers for Boots and oh, what an excellent time to happen as you are completely skint at the moment. or because you invented the perfect way to get joyfully tipsy and not completely wasted (usually this is based on the simple fact of not mixing every drink that comes to your mind, but stick on one).
So, no witty quotes about happiness I am afraid. It is something indefinable for me. Probably because when you are happy, you are not thinking that you are happy. You just feel it. Inside you. And no further explanations or intellectual definitions can describe it precisely. You cannot even say how long happiness lasts. It can be for a few moments (as we usually tend to suppress such a spontaneous feeling and stuff it with concerns, problems and many many thoughts) or it can be a general attitude in life...
A few days ago, I found myself surrounded by ponies. And I couldn't stop smiling. Simply like that. And that was an example of happiness.