1 Peter 1:13

13 Therefore, prepare your minds for action, keep sober in spirit, fix your hope completely on the grace to be brought to you at the revelation of Jesus Christ.

A better translation of the first line may be, “Gird up the loins of your mind,” which meant in those days to gather up one’s robes in order to run without hinderances, here applying to one’s thoughts, to keep our thoughts uncluttered or unhindered by the world. To “keep sober in spirit” means to be self-controlled and clear-minded, not given over to worldly and impure thoughts.

As for our hope, I think a better translation here is, “hope to the end, or “to keep your hope on.” The word “completely” I think is confusing. Hence, we are to fix our hope on the grace that will be brought to us when we see Jesus. The idea here is that we are to look more to the future, looking for His coming. Instead of always getting bogged down with all our earthly things, we ought to be keeping our mind on heavenly things.