Ouch. I have always thought of myself as an optimistic, glass-half-full kind of girl, but when I read this, it rang clear as a bell. I do this with my memories of things. Say there is a whole day I was hoping would be special. I get my hopes up, look forward to the day, make plans for it, and then when it comes I try hard to make that special day happen. If one thing happens that mars that special day, say an argument or an insensitive comment or someone getting upset, the whole special day is ruined in my mind, and I remember the day as being negative, rather than just one part of it.
This is a very discouraging way to live, because you end up with a whole mental scrapbook of events and moments (or even years) where all that remains in your mind is the bad stuff. It poisons out the good.
Instead of letting my natural thinking take over and leave with me unhappy memories (not to mention wanting to give up on trying anything special at all!), I need to have a positive filter instead. When I think through that day, the negative thing will be the first that comes to mind, since that's what I usually focus on, which blots the whole day. Being conscious of that tendency, however, I can decide that the one negative thing is not as big as all the good things. I can choose to either set that one thing aside, or even think of it as it really is--just one thing. I can change my choice of memories to a conscious focus on the good aspects of the day, making my memories actually more realistic, more happy, and me more likely to try again next time without dreading another terrible experience!