Reflection is remembering, pondering, recalling the goodness of our God. As we remember and reflect on His goodness, His grace, and His mercy in our lives, we need to be thankful and grateful.
There is a big difference between reflecting on past things in a positive way and thanking God for them, and dwelling on the past in a negative way and being stuck there. So let it go! The Holy Spirit will help us if we are willing. He will support us, guide us, and supply us with all that we need.