Did you know there is a biological reason for why we often tend to remember negative experiences much easier than positive experiences?
An example of how we do this is the classic saying (or belief) that "it rains every time I wash my car!"
Obviously, this is not statistically true in most cases, but even I agree that it definitely feels that way sometimes. In reality, it is because the times that it does rain after we just washed our car imprint in our memories more effectively than all the other times when we washed our car and it does not rain. Here's the scientific explanation why...
It can all be explained by early humans, when the brain was still making major changes to how it learned. Let's take the "Caveman" for example...
When he had a positive experience, such as finding a bush of edible berries, the brain did not store this information automatically; as it figured "if I found berries today, I will probably be able to find more tomorrow."
HOWEVER, when the caveman had a very negative experience, such as seeing a saber-tooth tiger (or whatever animal was dangerous back then), the brain learned to immediately store this knowledge in long term memory; as if to say "If I forget where this threat to my life is, there may be no tomorrow!"
Of course, that is an extreme example, but it demonstrates in a simple way how our brain immediately sends negative experiences that are "threatening" to the long-term memory. One of the unfortunate ways the brain has evolved since the caveman is our "threat assessment skill" has become skewed. Whereas threats to a caveman were those such as large dangerous animals, today we may perceive something like not getting invited to a party or it raining on our newly-washed car as a "threat." Therefore, too many negative experiences are perceived as "threatening" and thereby immediately sent into our long-term memory.
On the other hand, our brains do not do this automatically for most positive experiences. We have to work harder to store these in our long-term memory. Research suggest that if we can just "sit with" or "embellish" even the most minor positive experience, it can then start on the path to being stored in the long-term memory.
Here's a scenario that can illustrate how to do this.
Let's say you decide to take your car through the wash one day. Even though you have checked the weather forecast and it is not supposed to rain in the next week, your brain might immediately recall all the times when it has rained right after you got it washed, which could sometimes even lead you to thinking "there's no point, it'll probably just rain tomorrow anyway." For sake of this example, we'll assume you went ahead with the car wash anyway.
Now the important part, for each day that it does not rain after your car is clean (which will hopefully be several), you need to take extra time appreciating the fact that it did not rain. This can be as simple as admiring the shine of your newly washed car each day after you get home in the evening, accompanied by thoughts such as "that's awesome, I washed my car ___ days ago and it still hasn't rained!"
The more we can do this on a daily basis with all the small positive things that enter our lives, the more we can fill our long-term memory with delight.