I just finished reading Oliver Burkeman's book "The Antidote: happiness for people who can't stand positive thinking." I recommend starting with an interview like this one, and then go for the book if you want more. Hopefully, this post will give you all the "more" you need.
The basic message is simple, especially if you have been reading my blog or have studied human factors. Life is relative. We evaluate everything based on what we expect and have experienced in the past. So people in really poor communities are often very happy because they focus on things that are good, like family. Or they can compare their lives to reasonable expectations and have things come out just fine in comparison. Similarly, wealthy people are often unhappy because they compare themselves to people who are even more wealthy or create extremely high expectations that they can't live up to (at least not on a regular basis).
This follows the principle of hedonic adaptation. Hedonic adaptation is when a good thing becomes the norm and we start expecting it. So we stop appreciating just how good it is. It is essentially habituation to positive outcomes.
Now consider this in light of the basic premise of positive thinking. For any action there are a few possible outcomes. If you visualize the one you want the most and expect it to happen, there are two possible results. Either you get it, in which case you are happy but will eventually habituate to it. Or you don't get it, and fail in comparison to your expectation - leading to self-identity dissonance (which I have blogged before as an unhappy state).
If you are really visualizing the fantastic results that many positive psychologists recommend, then your odds are not very good in this game. You will experience failure more often than success. This can become a real burden on your self-identity and self-esteem.
His investigation for an alternative covers a variety of philosophies, ranging from Zen Buddhism to Stoicism. He proposes focusing on means rather than outcomes. Consider all of the actions you can take at the moment. Whichever one is likely to have the best result, and only an acceptable downside for failure, is the one you should do. And then whatever happens, it is the best outcome that was actually possible at that time. Then start the process over again. This not only means that you are very likely to have a good outcome, and therefore a positive experience and self-identity resonance, but it also helps you experience the moment because you are focusing on very short term goals.
So the "antidote" to positive thinking is not negative thinking. It is thinking about actions rather than outcomes. And setting reasonable expectations (or no expectations at all if you can pull that off). And if you need goals, make them short term and attainable.
What I liked about the book is that he bases his arguments on some real research that is well footnoted. What I didn't like is that he also uses a lot of anecdotes, which are just as much outliers and the positive psychology results he criticizes.