I do not know why YOU are or get depressed. I do know, however, that millions of people suffer from chemical imbalances which causes then to be depressed. Yes there are many (millions) who are depressed over emotional trauma/abuse/or a lot of bad things going on in their life - but if you feel you have no 'bad things' then it may very well be likely that you are chemically imbalanced. Some of the millions of chemically depressed people started out 'normal' meaning their brain chemistry was correct - however after a long period of sadness (loss of loved one, stress from work/loss of a job, long term illness, etc.) they eventually came to be depressed chemically because they were sad all the time. If you notice that depression hits you after meals, or at a certain time during the day you may have physical/chemical issues which are triggered by being tired, or eating the wrong kinds of foods. This and more information you need to ferret out yourself about you and when and how and where and under what circumstances you becomes sad or depressed. There are people out there who suffer from light depression - either the lack of light in the winter (those long nights and short cold days) or the reverse too much light can trigger chemical changes in the body which lead to depression. Thus if you find you are more depressed in summer than winter, or in winter than summer you may have SAD. It is important that you think long and hard about the conditions and periods of your depression - because you are going to need to tell a doctor who will be able to sit down with you and discuss treatment options and of course a diagnoses of the cause.

I would bet that you have never developed the habit of giving yourself things to look forward to. Start making a list of things you have to look forward to and see if it doesn't do wonders to improve your outlook... ...and if you have a hard time coming up with anything, try meditating on this thought for a while - there's ALWAYS something to look forward to...! ;-)

You probably have chronic depression ad have been depressed most of your life. You're probably getting flashbacks and memories of hard times. I'd recommend that you start reading jokes to make yourself laugh. (The jokes section of Answerbag is good). You should stop feeling so depressed; some antidepressants can help you with your depression.