I ONCE TOOK A CLASS called Silva Mind Control. It was kind of like self-hypnosis training and one of the suggestions we said to ourselves many times in the class was the following: Whenever we had a negative thought, we could say "cancel cancel" and it would nullify any influence that negative thought would have.
I don't know if that is true, but my wife and I use the phrase to help create a culture of optimism in our relationship. I might say something pessimistic and she'll say, "cancel cancel" and it will make me aware of what I just said. Or I might realize what I said as it comes out of my mouth, and I'll say "cancel cancel." It's short, quick, and gets right to the point. It's pretty handy.
You can use it in your own mind too, in two different ways. First, if you hear someone say something like, "Well, that's what happens when you get old," and you don't want to be influenced by that but you don't want to say anything out loud, you can simply say it to yourself. "Cancel cancel." Nullify such a pessimistic expression.
Another way you can use it in your own mind is when you say something or think something and you realize it is an overgeneralization, you can say to yourself, "cancel cancel," or even "overgeneralization." It's a way to help you clean up the thought-mistakes you habitually make.
To become less pessimistic, even if you aren't a pessimist, can protect your health and make you more effective in the world, and all you really have to do is catch yourself making thought-mistakes. That's it. Catch yourself doing it, and over time, you'll make those mistakes less often.