What is All eyes on the prize definition?

It is based on a passage of scripture, "Do you not know that in a race all the runners run, but only one gets the prize? Run in such a way as to get the prize. " 1 Corinthians 9:24.

The Apostle Paul is describing faith and salvation via the metaphor of race; i.e. its purpose and end goal.

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Also, "Keep Your Eyes on the Prize" is a folk song that became influential during the American Civil Rights Movement of the 1950s and 1960s. Although the song was composed as a hymn well before World War I, the lyrics to this version were written by civil rights activist Alice Wine in 1956. It is based on the traditional song, "Gospel Plow", also known as "Hold On", "Keep Your Hand on the Plow", and various permutations thereof.

Note: what I just posted above is the historical background and original use of that expression. however, despite its Christian origins, the phrase has come to be used in many secular situations for non-spiritual purposes. For instance, the CEO of a major corporation could say to his investors at a shareholders meeting, "We'll be freezing new hires for the year ahead and closing a few of our stores during these challenging economic times. We need to keep our eyes on the prize and do what it takes to ensure a solid future." That's an unfortunate misappropriation of this overtly spiritual idiom, but, it may remind a few of the shareholders about their faith and that may in turn motivate them to work to help that corporation do things in a just and ethical manner. To a child, it would mean to keep optimistic that you will be successful.