Living Life with no Regrets

Everyone has things in their lives that they wish they wouldn't have done or said. But the truth is we can't undo what's been done or said. What we can do is repent of past sin and mistakes because we, as Christians, are forgiven and justified in the sight of God by the blood of Jesus Christ!
So...
Since we are forgiven of our past sins and mistakes, then why do we continue to look back to the past and long to redo or undo what's already been done? These things in our past that can't be undone are holding us back from living completely for the glory of God and sharing the Gospel of Jesus Christ.
If we're going to follow Jesus and be His disciple, then we need to put all of these things that we hold so close behind us, and go forward in our walk with Him and stop longing to go back to the past.

Yet another said, “I will follow you, Lord, but let me first say farewell to those at my home.” Jesus said to him, “No one who puts his hand to the plow and looks back is fit for the kingdom of God.”
(Luke 9:61-62 ESV)