One of my favorite sayings is from the late Dallas Willard; “What you focus on determines what you miss.”
What he is saying is if you put all your focus (all your attention) on a single subject, then you are less likely to see other subjects. An athlete who only works on upper body will neglect the lower body.
The person who scours the news for scandals will miss all of the good things that are recorded. Etc.- William Moller