In a book called "Stumbling Towards Happiness" the author explores with the reader what are the key things that make us happy. One of the things examined was a set of conjoined twins. THe tiwns had no desire to be separated and were extremly happy just as they were. Many people would say they are happy because they don't know any better, but is that really the case? THey always have a companion, they are never alone. Their limits are met with a companion to "think" through the obstacles and barriers?
Happy is a subjective term. Perhaps the question should be what could you deal with better?