Positive thinking is a catch cry and common philosophy throughout society. We often tell ourselves and others to think positively, especially when the chips are down. However, if you have ever tried to edit your thoughts or speech to only think positive thoughts you may have first got tired, then irritated, and then had a hopefully minor explosion of negativity. This is because ignoring the unpleasant doesn't make it go away, even if you try to put a positive spin on it. It will bubble up like a revolution of the downtrodden. In fact, trying to Pollyanna in a volatile situation can actually be dangerous to the person or others (like trying to pat a rabid dog).
Also positive thinking vs negative thinking is very dualistic in it's philosophy (this is good/this is bad), and is judgement based. It is a very black and white (as opposing extremes) in it's scope. You can only be wrong or right. The scope is very limited. Here is an alternative that allows the full spectrum.
The idea is Creative Thinking. If you have a problem to solve, you work beyond the scope of positive and negative, and try to start to look at the full spectrum of options available to come up with a solution. It is the domain of brainstorming. Think of the elements to the objective that are necessary or fixed, and then bring other elements in and out of your thinking until you come up with a solution that makes you feel like it could be beneficial or constructive. You, if you want, are looking for something that works. Or you have the options of leaving it as it is, abstracting because you can, or giving it to someone else etc. The full gamut of possibility is there. It is absolutely necessary in creative thinking to think outside the box, even if the end conclusion is conservative.
If you have difficulty thinking beyond the normal viewpoint (whatever that is for you and yours), look into the ideas behind the Dada art movement. Alternatively, flip a coin while deciding what to do about a current problem, or what to plan to do in the next year. It isn't necessary to do what the coin decides, but it helps to think about it from an angle you may not have looked at from before. Also, imagining you are another person in the situation helps with thinking outside the box in a relevant way.
It is fine also to think in the black and white, positive and negative way as well. But I find it restrictive in the dualism, and two dimensional. I personally prefer the full spectrum of Creative Thinking. It accepts the rainbow of existence, including it's darknesses. And accepting all the elements is a better way to more thoroughly solving the problem.