What separates us human from other animals is emotion. We will be happy when something nice happens to us, but would also feel sad about something bad too. There are many different ways from different people to over come their sadness. Some can solve their problems very well and stay happy most of the time, but others who were not so well equipped in tackling problems finding life hard to enjoy. And they would feel sad all the time. These is all about way of people's thinking. Different way of thinking will see and react to things and situation differently too. And this is also where philosophy comes into effect. people have a great mind about philosophy can see things and situation more clearly and have better understanding about them, Therefore they would not get upset easily or less upset, thus staying in better mood all the time, while others haven't this abilities seeing things and situations hopelessly confused. Treating small setback as huge failure and bigger problems like the end of the world. How can they not feeling sad all the time then?
Although I am not a philosopher, I have my own way of looking at adverse situations too. When I am sad, I tell myself don't be sad, things could have been worse. Do not always think that you have got nothing to cheer about because there are many who are much worse than you. Don't you think that you are sad, for there are many others are sadder than you too. And my motto is don't look up but look down, because no matter how good you are and there will be always someone better than you, ahead of you and above of you. But instead, if I look down and I can always see that there are always someone below me and behind me, that way I can feel that I am always ahead and above of some others! Then I would be less sad and can feel more happy most of time!