Have any of you ever experienced mood swing or feel very down at times? For me, sometimes I will have bad mood or feel down and just don't feel like doing anything. Is it common? It takes a cheerful and optimistic person to stay happy all the times which I find it very difficult to stay happy everyday. Any of you have any "secret" remedy to stay happy all the times or at least stay cheerful in difficult times? Do share with me, I would love to hear from you.