Now, let me sound like an expert for this post, at least for this post, because I am not an expert in any way.
There's an old and effective tool to gauge the "pessimisticity" and "Optimisticity" of an individual. Ask them this question:
"How do you describe a glass with half of its volume occupied with water? Half Empty or Half Full?"
If you are going to think of it, both answers are correct. You can call it half empty, or you can call it half full.
But here's the twist:
If you answered half empty, that means, you are more of a pessimistic person. That means, you think negative because you focus on what you don't have. If you don't have money, your focus is on money. If you don't have lovelife, your focus is on your lovelife. If you don't have a career, your focus is on your career. And you know what's more frustrating? When you can't put everything on the right track which is more likely to happen because you focus on the negative side. If you say the glass is half empty, it is good to say that you considered it empty.
On the other hand, when you say half full, you are somebody on the positive side. You focus on what you have. It is just a matter of diversion. If you don't have lovelife,so what?, at least you have money. If you don't have money, so what?, at least you have friends. That is how you think. You are diverting your thoughts on things that you have instead of things that you don't have. And the interesting part here is that, you will gradually get everything you want, as in everything because you are a positive thinker. You are attracting everything you want because you are counting your blessings. It is biblical and we even have a church hymn on that.
On my own standard, I can determine a person based on its judgement. Supposed you see a white piece of paper with a black dot at the middle, what's the first thing that comes in your mind?
If your attention focused on the black dot at the middle of a paper, meaning, you are a person who compromises the 99% goodness and considered the 1% badness. You think everything should be perfect and you can easily judge a person with a single mistake.
On the contrary, if you think you can still use the paper since the majority of the area is clean and white, you are a considerate individual. You consider but of course you don't tolerate. While a single black mark could not affect your judgement, you will find a way to make it useful or at least make it unnoticeable.
While these questions can be a useful tool to know yourself better, only you can answer and gauge how pessimistic or optimistic you are. We need to know where we stand so we know what to correct and what to enhance.
Think Positive and think good. Good things will only happen if you know how to control your thoughts.