Remember that you were slaves in Egypt, and follow carefully these decrees. Deuteronomy 16:12 NIV
I have had some very bad experiences with food. In fact some of those experiences were so bad that a focused thought on the exact nature of the experience produces a feeling in my stomach that matches the original feeling that I had. This is an example of the fact that our minds are so powerful that they can cause our bodies to respond to a thought in a manner that makes us feel as if we had actually relived the experience.
God wanted the people to remember that they had been slaves in Egypt. There were certain observances that they were to practice as a part of their remembering that included offering sacrifices and giving offerings. Why so much emphasis on remembering their painful past?
It certainly would remind them that God had been a loving God that did not forget them or ignore their suffering. But their remembering the very unpleasant time of slavery would also help them remain grateful for their current situation. They were not yet in the land of promise. They did have everything they desired. But they were also no longer being asked to make bricks without straw by brutal slave masters. Their lives were greatly improved.
Perhaps none of us have been slaves. But each of us has a memory of a circumstance or situation that was unpleasant in our lives. We all have had moments when we were in a place that was much worse than the place that we currently occupy. The fact that our past experience did not kill us means that we have something to be grateful for. We also have the basis to believe that the same God that brought us out last time will bring us out this time.
"God, help me to remember where I have been and to be more grateful for where I am. Amen"