“One thing I do: forgetting what lies behind and reaching forward to what lies ahead, I press on toward the goal for the prize of the upward call of God in Christ Jesus.” (Philippians 3:13b-14 NASB)
Why do failures linger? Failures take on a life of their own because the brain remembers incomplete tasks or failures longer than any success or completed activity. It's technically referred to as the "Zeigarnik effect." When a project or a thought is completed, the brain places it in a special memory. The brain no longer gives the project priority or active working status, and bits and pieces of the achieved situation begin to decay. But failures have no closure. The brain continues to spin the memory, trying to come up with ways to fix the mess and move it from active to inactive status.
-- Perry Buffington