Matthew 6

Nephi wrote -

"...Wherefore, if ye shall press forward, feasting upon the word of Christ, and endure to the end, behold, thus saith the Father: Ye shall have eternal life."  (2 Nephi 31:20)

In my mind, the reason we are to feast upon the word of Christ is so we know how to endure to the end.  I find the so called "Sermon on the Mount" to provide much of this word.  For example, one being -

"The light of the body is the eye: if therefore thine eye be single, thy whole body shall be full of light.
23 But if thine eye be evil, thy whole body shall be full of darkness. If therefore the light that is in thee be darkness, how great is that darkness!"  (Matthew 6:22–23)

Obviously if our eyes focus or be single to the glory of God, we will be full of light which helps us endure to the end.