In our lives, we live through many experiences, some which are pleasant, and some that are not. Some would say this is due to the effects of causality. We must have faith in God, and open our minds to what is occurring in our lives. From these occurrences in our daily lives, we must ponder if they are guidance from God; and sweep our evils (greed and arrogance) from our minds. It serves no purpose to worry about what we cannot change (causality, karma). But we can influence our future by eliminating greed and arrogance from our minds today. This is a verse from the Osashizu:
On your long journey, you have sunny days and cloudy days, rainy days and windy days. You have all sorts of days. From this, understand. If you try to settle things by allowing the mind to have spaciousness and openness, then things will settle.
Summary: You cannot change what you have done in the past. But you can influence your future by what you think or act today.