The invisible gorilla experiment is one of the best known psychological experiments of all time. Only about 50% of the people who watch the video actually see the gorilla.
This is an amazing ability. We can focus so intently on something that we are actually blind to everything else.
The challenge. Focus on the right things.
After this I beheld, and, lo, a great multitude, which no man could number, of all nations, and kindreds, and people, and tongues, stood before the throne, and before the Lamb, clothed with white robes, and palms in their hands;  And cried with a loud voice, saying, Salvation to our God which sitteth upon the throne, and unto the Lamb.Revelation 7:9-10 KJV