If we dwell on the past, whether it be good memories, or bad memories, we will not be able to press toward the mark for the prize in the High calling of God in Messiah... I have definitely been guilty of this throughout my life, and battle with nostalgia from time to time. We must remember that we are a New Creature, and old things are passed away!! HalleluYah!

Philippians 3:13-15
[13]Brethren, I count not myself to have apprehended: but this one thing I do, forgetting those things which are behind, and reaching forth unto those things which are before,
[14]I press toward the mark for the prize of the high calling of God in Christ Jesus.
[15]Let us therefore, as many as be perfect, be thus minded: and if in any thing ye be otherwise minded, God shall reveal even this unto you.