I have just realized one thing. We all know that life is composed of ups and downs. It's a balance. But people pick up or choose what facet of their life they want to show among the public/people/environment.
There's no such thing (I think) as people who are always happy all the time. Or you see them as always cheerful and happy and they don't seem to have any problems or that they don't ever feel sad or distressed. It's just that, they choose to show the happy side of their life. They may have some sorrows and problems that may have been concealed. That doesn't mean they have more happiness than others. It's just that they choose to show it more and can be seen by more people.
Also, those people who you think must have been very lonely or sad or suffering because of the things that he or she have shown, doesn't mean that he or she is always like that. It just means that he or she chooses to show her negative emotions and feelings while he or she may feel happiness or joy that may not be seen by most people. I think this is how life goes. It's not really a matter of fact but rather a result of introspection, observation and perception. It is my own opinion. At least that's how I view it. One may contradict as he or she cannot relate to this conviction but for me, this is how I perceive it. People choose the emotion, whether negative or positive, they want to show to the public. It's a matter of choice. It may not be a subconscious choice. The mind sometimes play tricks on us and we tend to become impulsive on what emotions we want to show. Especially if the emotion is too strong.
On people having psychological problems, especially those people with manic depressive disorders, umm, that's another side of the story. Those people who are suffering from hyperactivity, over-excitedness?(i don't know the term...it's kind of hard to explain...i just read it from wikipedia and i kind of forgot), depression disorder...hmm...i don't know how their minds work actually but I do want to know. It's another topic. No wonder I am so fond of Psychology. This is another topic to delve on.