I'm sure everybody had this experience in one way or another: You learn about a new thing, and all of a sudden this thing appears to be everywhere.
For example, I did some research on the best noise-canceling headphones on the market, because I wanted to buy a pair. Immediately, I started seeing people wearing them everywhere. It was like the world had suddenly decided to adopt noise-canceling headphones.
Obviously, this wasn't the case. Rather, my focus had shifted. It's a funny trick our mind plays, and it can work for or against us.
How it can work against you:
Suppose you meet someone for the first time and get a slightly negative impression because of something small he does. Subsequently, you'll interpret everything that person does with a negative bias. Your focus won't let you see all the positive things he is doing.
How it can work for you:
You can intentionally shift your focus and influence what you notice in the world around you. It's more powerful when you focus on something specific.
For example, commit to noticing only all the positive things your partner does for you and your family. Try that for 72 hours and make a mental note of as many things you can find. How much better do you feel about your partner after this exercise? Do you still feel like nagging about that one time your partner forgot to take out the trash? Likely not! Your focus has successfully shifted.