Two passages have been ringing in my ears (and heart)...
Mark 10:28-31 Peter began to say to him, “See, we have left everything and followed you.” Jesus said, “Truly, I say to you, there is no one who has left house or brothers or sisters or mother or father or children or lands, for my sake and for the gospel, who will not receive a hundredfold now in this time, houses and brothers and sisters and mothers and children and lands, with persecutions, and in the age to come eternal life. But many who are first will be last, and the last first.”
So, it makes sense to me why Peter would have written this years after Christ said this to him.
2 Peter 1:8-11 For if these qualities are yours and are increasing, they keep you from being ineffective or unfruitful in the knowledge of our Lord Jesus Christ. For whoever lacks these qualities is so nearsighted that he is blind, having forgotten that he was cleansed from his former sins. Therefore, brothers, be all the more diligent to make your calling and election sure, for if you practice these qualities you will never fall. For in this way there will be richly provided for you an entrance into the eternal kingdom of our Lord and Savior Jesus Christ.