"I said that in the moment," is a common excuse. There is often truth in that our speech in the moment may not reflect how we feel. But at times our speech in the moment reveals more of our true nature.
It is difficult at times because we do not like some things about ourselves. We might prefer to believe the prettified version of ourselves we present to others on a dally basis is our true nature. We often refuse to admit our problems.
The reality is we are quick to excuse ourselves and blame this or that and not see it as a reflection of ourselves. Thus a lack of time to think is an excuse for lack of action or slightly improper action.
Sometimes the reality is what we do without a lot of time to think says more about us than what we do after much thought. You see it is sometimes easy to convince ourselves to do the right thing after much thought, but if we must do the right thing now or not at all we often fail.
We always like to think well of ourselves and thus we create many grand excuses for ourselves. They are not needed as God knows our nature and wishes to save us anyway. But we always continue to like to prettify our lives.
What happened in a moment or what we failed to do often speaks to something in our nature. As Christians we are being renewed by Christ, but we also have our sinful nature which is not fully transformed. We often like to act as if our lives are far more sanctified then they are.
The truth of our ethical lack or even awareness that there may be something ethical we missed doing is difficult for us. We are often quick to judge others and quick to forgive ourselves.
The bible is very difficult in that it asks us to be quick to forgive others and more harsh on ourselves. It is of course entirely fair since God has forgiven us in a completely unqualified way.
It is not like we come to God and show a set of credentials and see if we may be forgiven. If we truly come to God for forgiveness in that moment we are already forgiven. God saves all who knock and ask for the forgiveness that comes through faith in Jesus.