Many times gurus and coaches will tell you not to concern yourself with looking back. Just keep your head down and focus on what you can do now in order to move forward. Some think looking back is a distraction. Well...
Recently I did one of the hardest things I've ever done in my life. I cycled through Tuscany. For six days (one day off in the middle) I cycled through what some would call rolling hills. I would call them baby mountains. Regardless, it was no joke. An intensely physical venture, but more of a mental strengthening exercise.
Day 1 was cool and relatively easy. I'm thinking, I got this. But Day 2 wasn't my finest hour. The mental head game I needed to get up the third major incline of the day was not yet developed. I had no idea how to keep going through the pain. I didn't know how to get out of my head. I didn't know how to regulate my breathing. I had no idea how to psyche myself into doing one more incline. So I walked the last couple of miles that day. I was disappointed in myself.
By Day 3, my head game was better. One of our amazing guides and instructors told us, "Even if you don't want to look at the top of the hill as you're riding up, every now and then turn around to see how far you've come." That advice was like gold to me. Looking at the top of the hills tended to get in my head, so I rarely did. But glancing back to see the progress I'd made gave me everything I needed to push forward. And I was able to ride, not walk, the rest of the tour.
So if you feel the need to look back, make it a quick glance with the sole purpose of taking inventory of how far you've come. And then use it as inspiration to push you forward.