One of my favorite lines from the tv show Vikings happens when Ragnar and his fleet are leaving home. Two boys are watching the shore and Ragnar says, "Don't waste your time looking back. We're not going that way."
Why Looking Back is a Waste of Time
While I actually think it's a good idea to look back at the old year as it's moving away, review a dying relationship for learning moments, and just to keep in touch with my roots, habitually looking back is not a great habit.
Why it's best to let the past go
In reality, this is the only moment there is.
Life is made up of moments. Any moment you are not here is a moment that's not lived.
Your past is rich with memories, lessons, love, and struggles. You can bring those moments with you and allow them to enrich the present. If you don't like the present moment, use them to build a future that you enjoy.