Dany provided something a little different, not what happiness is to her but an explanation of the unique Brazilian concept of 'saudade'.
Saudade is the emptiness, the transformation, the alchemy that remains in you after the absence of people, experiences, situations. It is when your heart and mind travel involuntarily when you close your eyes for more than two seconds, searching the memory for that feeling that was already part of you. its more than nostalgia or melancholy. There is a particular pride in feeling 'Saudade': it means that you lived, felt. If a brazilian says "Sinto saudade de voce" it means that you are a part of his memory.