Looking around, it seems as though everyone around me is diagnosed with depression or bipolar disorder these days. Did it ever occur to anybody that maybe shifts in mood are normal? I feel like we're a bunch of leopards looking at each other and screaming, "Oh shit dude, you got a spot!" Feeling good all the time despite what's going on in your life, now THAT sounds wrong to me. From my experience, being labeled as something like depressed can start people down a pretty harmful cycle. First, when you treat something normal (like the occasional bad mood) as something that's not normal, you effectively ostracize yourself and make yourself feel like some kind of leper. This can damage your self esteem which can spiral you into an even deeper depression. Second, once you've established yourself as a "depressed" person, you can then start to use it as a crutch. Although many don't like to admit it, depression can be a useful tool to let you know when there's some much needed change in your life. If it weren't for feeling down, why would you venture out of your comfort zone? Unfortunately, it loses its usefulness once you use it as a crutch and tell yourself that "you're not depressed because you're unemployed, lonely, and/or uneducated, you're depressed because your brain chemistry is fucked up." See how easy it can be to resort to a complacent position in life and fall into stagnation? Instead of doing this, try taking a bad mood in stride and understanding why you're thinking that way. And go for a jog! Exercise is proven to be beneficial for relieving symptoms of depression.
I am not a Dr. Phil, nor do I plan on becoming one. These are just my thoughts after seeing many friends/family deal with depression. Obviously, there are exceptions.