Some people say a person is either a half glass fuller or a half glass emptier. Basically, they're describing whether that person is positive or negative.
I would have to say that when the glass is half full or half empty the glass should in reality be dead even. It's neither fuller nor emptier. In that light, I would ask how often are situations dead even? Usually when an occasion comes up that this may be used, the situation is either positive or negative. It is never actually in between as the phrase so clearly implies by the word "half".
So now we have two situations. We have a negative situation in which a person is positive (half fuller), and we have a positive situation in which a person is negative (half emptier). So let me ask you this: if the situation were perfectly positive...could there be half glass empty, negative person? And if there were a perfectly negative situation could there be a positive person? The answer is no. If it were perfectly positive there would be nothing to be negative about, and if it were perfectly negative there would be nothing to be positive about.
My point is that no situation is ever truly positive, negative, or in between. If a good thing happened you can always find the bad. In this, know that there will always be a negative side to a good thing and a positive side to a bad thing. It all depends on the situation. What's good for you isn't always best for everyone. Keep that in mind as you live your life. Something bad that happens to you could very well mean something good for someone else. Lastly, I would encourage you to always be positive because it breeds success and healthy living, but do not be ignorant of the negative. Perspective is key.