'Negativity Bias' is a commonly acknowledged psychological phenomenon. Even when they're equal in intensity or magnitude, a negative experience will be weighted with more emotional significance than a positive one.
I guess it's just a part of our physiology as humans, and likely an evolutionary response so we're more alert, aware and emotionally prepared for negative experiences that potentially pose a risk to our survival. Quite difficult to overcome as you might imagine.

Nevertheless, this is a great, insightful article that I'm sure will go some way to helping people address the issue and begin to overcome whatever anxieties they might have as a result of negative experiences - I have plenty myself.

I like the idea of your 'saving thought' - Very similar to the idea of going to your 'happy place' mentally when distressed.

Thanks for sharing :)