Looking back slows down forward progression.
Have you ever tried to walk in the opposite direction that you were looking?
If not, try walking forward while looking back and then compare your speed to walking forward while looking forward.
What you'll find is that speed is on your side when both your vision and effort are on one accord. Now you're probably thinking that makes perfect sense, but consider how often we say we are ready to move on, all the while looking back.
We look back at how good things were. We look back at how bad things were. We wonder what would've happened if we acted in a certain way.
Reality check - it happened. Bad, good, and in between. Looking back won't change it and nor will it bring anything back. The good news? Better will happen and it will happen faster if you're looking forward to it in expectation.
Look in the direction you're going and the progress you are seeking will follow. Expect your future to be brighter than your past, and expect that your past has made you strong enough to get past anything unexpected.